port ci updates to docs build, set sphinx to older, compatible version

Author: JacksonBurns

.github/workflows/docs.yml

@@ -22,7 +22,7 @@ jobs:
           git config --global user.email "github-actions@github.com"
 
       - name: Clone RMG-Py
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
@@ -32,23 +32,24 @@ jobs:
           environment-file: environment.yml
           miniforge-variant: Miniforge3
           miniforge-version: latest
-          python-version: 3.9
+          python-version: "3.9"
           activate-environment: rmg_env
-          use-mamba: true
+          auto-update-conda: true
           show-channel-urls: true
+          conda-remove-defaults: "true"
 
       - name: Make libtiff Symlink to Avoid Runner Bug
         run: | # This action may need to be removed/adjusted in future runs.
           if [ ! -f /usr/lib/x86_64-linux-gnu/libtiff.so.5 ] && [ -f /usr/lib/x86_64-linux-gnu/libtiff.so.6 ]; then sudo ln -s /usr/lib/x86_64-linux-gnu/libtiff.so.6 /usr/lib/x86_64-linux-gnu/libtiff.so.5; fi
           find /usr/lib -name libtiff*
 
       - name: Install sphinx
-        run: mamba install -y sphinx
+        run: conda install -y sphinx~=5.0
 
-      - name: Mamba info
+      - name: conda info
         run: |
-          mamba info
-          mamba list
+          conda info
+          conda list
 
       - name: Clone RMG-database
         run: |