fix: pin pygments<2.20 in mkdocs workflow

Author: HavenDV

.github/workflows/mkdocs.yml

@@ -49,7 +49,7 @@ jobs:
         run: |
           python -m venv myenv
           source myenv/bin/activate
-          pip install mkdocs-material
+          pip install mkdocs-material 'pygments<2.20'
           mkdocs build -d ./_site
           
       - name: Upload artifact