build(deps): update mkdocs-gen-files requirement in /pywry/docs (#19)

Updates the requirements on [mkdocs-gen-files](https://github.com/oprypin/mkdocs-gen-files) to permit the latest version.
- [Release notes](https://github.com/oprypin/mkdocs-gen-files/releases)
- [Commits](oprypin/mkdocs-gen-files@v0.5.0...v0.6.1)

---
updated-dependencies:
- dependency-name: mkdocs-gen-files
  dependency-version: 0.6.1
  dependency-type: direct:production
...

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Co-authored-by: Danglewood <85772166+deeleeramone@users.noreply.github.com>

Author: dependabot[bot]

pywry/docs/requirements.txt

@@ -8,7 +8,7 @@ mkdocstrings[python]>=1.0.4
 griffe>=2.0.2
 
 # For cross-references
-mkdocs-gen-files>=0.5.0
+mkdocs-gen-files>=0.6.1
 mkdocs-literate-nav>=0.6.3
 mkdocs-section-index>=0.3.12