chore(deps): update captcha requirement in /api in the pip-api group

Updates the requirements on [captcha](https://github.com/lepture/captcha) to permit the latest version.

Updates `captcha` to 0.6.0
- [Release notes](https://github.com/lepture/captcha/releases)
- [Changelog](https://github.com/lepture/captcha/blob/master/docs/changelog.rst)
- [Commits](lepture/captcha@v0.5.0...v0.6.0)

---
updated-dependencies:
- dependency-name: captcha
  dependency-type: direct:production
  dependency-group: pip-api
...

Signed-off-by: dependabot[bot] <[email protected]>

api/requirements.txt

@@ -1,4 +1,4 @@
-captcha~=0.5.0
+captcha~=0.6.0
 celery~=5.4.0
 coverage~=7.5.4
 cryptography~=42.0.8