Fix small typo in error response

[gilfaizon]

Overview

Noticed a typo when investigating a ticket, figured I'd fix it.

Acceptance criteria

Corrects a typo, nothing breaks.

Testing plan

Text-only change, no testing was done.

Risks

Little risk, text-only. Unsure if this needs to be declared in the changelog.

Metrics

None

References

N/A

Checklist

• I added tests for this PR's change (or explained in the PR description why tests don't make sense).
• If this PR introduced a user-visible change, I added documentation into docs/.
• If this PR added docs, I added links as appropriate to the user manual's ToC in docs/README.ms and gave consideration to how discoverable or not my documentation is.
• If this change is externally visible, I updated Changelog.md. If this PR did not mark a release, I added my changes into an ## Unreleased section at the top.
• If I made changes to .fossa.yml or fossa-deps.{json.yml}, I updated docs/references/files/*.schema.json AND I have updated example files used by fossa init command. You may also need to update these if you have added/removed new dependency type (e.g. pip) or analysis target type (e.g. poetry).
• If I made changes to a subcommand's options, I updated docs/references/subcommands/<subcommand>.md.

[csasarak]

Thanks for contributing, when all the checks pass feel free to merge or contact me and I can take care of it.