Bump yaml from 2.9.0 to 2.9.1

Bumps yaml from 2.9.0 to 2.9.1.

• Release notes
• Commits

updated-dependencies:

• dependency-name: yaml
  dependency-version: 2.9.1
  dependency-type: direct:development
  update-type: version-update:semver-patch
  ...

Signed-off-by: dependabot[bot] support@github.com
Co-authored-by: dependabot[bot] 49699333+dependabot[bot]@users.noreply.github.com

PR https://github.com/mantisbt/mantisbt/pull/2293