Update docs workflow

Author: deathaxe

.github/workflows/deploy-gh-pages.yml

@@ -18,7 +18,7 @@ jobs:
         with:
           fetch-depth: 0
       - name: Set up Python
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v3
         with:
           python-version: '3.8'
       - name: Install MkDocs

mkdocs.yml

@@ -29,14 +29,14 @@ plugins:
 
 markdown_extensions:
   - markdown.extensions.admonition:
+  - markdown.extensions.footnotes:
   - markdown.extensions.smarty:
       smart_quotes: false
   - pymdownx.betterem:
+  - markdown.extensions.abbr:
   - markdown.extensions.attr_list:
   - markdown.extensions.def_list:
   - markdown.extensions.tables:
-  - markdown.extensions.abbr:
-  # - pymdownx.extrarawhtml:
   - pymdownx.superfences:
   - pymdownx.highlight:
       css_class: codehilite
@@ -62,7 +62,7 @@ markdown_extensions:
   - pymdownx.tasklist:
       custom_checkbox: true
   - pymdownx.striphtml:
-      strip_attributes: ''
   - pymdownx.keys:
       separator: "\uff0b"
   - pymdownx.details:
+  - pymdownx.saneheaders: