fix: Ignore changes to attributes

[grahamhar]

When a github_repository_file resource was created with a provider version older than 6.3.0 the new attributes added in that version causes a new commit to be created when there should be no changes to the file.

Resolves #2400

---

Before the change?

On an existing resource the github_repository_file is updated due to new attributes.

After the change?

On an existing resource the github_repository_file is note updated due to new attributes.

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• [] Yes
• No

---

I have tested this against a resource created using the older provider version, then using this codebase built locally.
Output of test run

TF_ACC=1 go test -v ./... -run "^TestAccGithubRepositoryFile$"
?       github.com/integrations/terraform-provider-github/v6    [no test files]
=== RUN   TestAccGithubRepositoryFile
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files/with_an_anonymous_account
    resource_github_repository_file_test.go:81: anonymous account not supported for this operation
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files/with_an_individual_account
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files/with_an_organization_account
=== RUN   TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create
=== RUN   TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create/with_an_anonymous_account
    resource_github_repository_file_test.go:162: anonymous account not supported for this operation
=== RUN   TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create/with_an_individual_account
=== RUN   TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create/with_an_organization_account
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted/with_an_anonymous_account
    resource_github_repository_file_test.go:251: anonymous account not supported for this operation
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted/with_an_individual_account
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted/with_an_organization_account
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist/with_an_anonymous_account
    resource_github_repository_file_test.go:335: anonymous account not supported for this operation
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist/with_an_individual_account
=== RUN   TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist/with_an_organization_account
--- PASS: TestAccGithubRepositoryFile (131.83s)
    --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files (27.28s)
        --- SKIP: TestAccGithubRepositoryFile/creates_and_manages_files/with_an_anonymous_account (0.00s)
        --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files/with_an_individual_account (13.75s)
        --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files/with_an_organization_account (13.53s)
    --- PASS: TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create (31.28s)
        --- SKIP: TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create/with_an_anonymous_account (0.00s)
        --- PASS: TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create/with_an_individual_account (15.87s)
        --- PASS: TestAccGithubRepositoryFile/can_be_configured_to_overwrite_files_on_create/with_an_organization_account (15.41s)
    --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted (39.36s)
        --- SKIP: TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted/with_an_anonymous_account (0.00s)
        --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted/with_an_individual_account (19.96s)
        --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files_on_default_branch_if_branch_is_omitted/with_an_organization_account (19.40s)
    --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist (33.91s)
        --- SKIP: TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist/with_an_anonymous_account (0.00s)
        --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist/with_an_individual_account (16.75s)
        --- PASS: TestAccGithubRepositoryFile/creates_and_manages_files_on_auto_created_branch_if_branch_does_not_exist/with_an_organization_account (17.16s)
PASS
ok      github.com/integrations/terraform-provider-github/v6/github     132.904s

[kfcampbell]

Thank you @grahamhar! I appreciate the timely fix and attention to detail.