chore: Add requirements-dev.txt exception to header-checker-lint.yml (#10300)

* Update header-checker-lint.yml

`requirements-dev.txt` exists in some samples, and should also be ignored in license header checks.

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: kweinmeister

.github/header-checker-lint.yml

@@ -9,8 +9,9 @@ allowedLicenses:
 
 ignoreFiles:
   - "**/requirements.txt"
-  - "**/requirements-test.txt"
   - "**/requirements-composer.txt"
+  - "**/requirements-dev.txt"
+  - "**/requirements-test.txt"
   - "**/__init__.py"
   - "**/constraints.txt"
   - "**/constraints-test.txt"