Bump pygccxml from 2.6.0 to 2.6.1 in /.github (#299)

Bumps [pygccxml](https://github.com/CastXML/pygccxml) from 2.6.0 to 2.6.1.
- [Release notes](https://github.com/CastXML/pygccxml/releases)
- [Changelog](https://github.com/CastXML/pygccxml/blob/develop/CHANGELOG.md)
- [Commits](CastXML/pygccxml@v2.6.0...v2.6.1)

---
updated-dependencies:
- dependency-name: pygccxml
  dependency-type: direct:production
  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>
Co-authored-by: berndgassmann <bernd.gassmann@intel.com>

.github/workflows/requirements.txt

@@ -3,7 +3,7 @@ Markdown==3.7
 markdown-include==0.8.1
 mdx_truly_sane_lists==1.3
 mkdocs==1.6.1
-pygccxml==2.6.0
+pygccxml==2.6.1
 Pygments==2.18.0
 pymdown-extensions==10.12
 pyplusplus==1.8.5