Marking public key non sensitive

[saiyam1814]

Closes #58

[zulh-civo]

LGTM

@saiyam1814 can you provide before vs after logs in your future PRs? You can refer this PR as example. I'll include this for you for this PR.

Before:

# civo_ssh_key.my-user:
resource "civo_ssh_key" "my-user" {
    fingerprint = "SHA256:ZLrkWwLOvL+w5U9sY3Wg95x28CUsletfB0gJiUryrcc"
    id          = "5dfc720b-9e8d-4c04-a89f-d0687da6e761"
    name        = "terraform-test"
    public_key  = (sensitive value)
}

After:

# civo_ssh_key.my-user:
resource "civo_ssh_key" "my-user" {
    fingerprint = "SHA256:ZLrkWwLOvL+w5U9sY3Wg95x28CUsletfB0gJiUryrcc"
    id          = "271fee73-3449-49b7-9c47-139c7f8fa7aa"
    name        = "terraform-test"
    public_key  = <<-EOT
        ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCrW3f2+YQzqbHd9l/giquEflzm7Xpir1GCpP6CqTDAzB2xUmYsYUjbkw17McQJnAjoeXcYzqgitaRsfRZsfSDKokPNgBEm2gyiOaOfyr38c8QWR37gHDxWa3tt2UUV7Vvadig1bH3oRGKF/IsoyYToxhHQOCDmUeJ7b7CY8HWKvC4/vPI2Ev8OApLWwW2kRMZv26KsTbQVSbbquAl8UJySHbCct+TMTLjirzYZF2N2NLUo7sWLT5Oo774CdFOs3ksrrrNMxCU+Y329WVtz9wrThHt1eGey/3/tJEgyokBM5jmj3E2lu0KOY413cqVzNeV18lfSX+cn84ezPFWic90D zulh@Zulhs-MacBook-Pro.local
    EOT
}