fix(ci): use mkdocs gh-deploy directly

we need to install pems_data before mkdocs can build

the mhausenblas/mkdocs-deploy-gh-pages action step seems to either
ignore or not see that installation

so make the actual deploy work more like the preview deploy,
just install dependencies and use mkdocs directly

Author: thekaveman

.github/workflows/mkdocs.yml

@@ -97,12 +97,10 @@ jobs:
             "**/pyproject.toml"
             "docs/requirements.txt"
 
-      - name: Install local pacakges
+      - name: Install MkDocs requirements
         run: |
-          pip install ./pems_data
+          pip install ./pems_data -r docs/requirements.txt
 
-      - name: Deploy docs
-        uses: mhausenblas/mkdocs-deploy-gh-pages@master
-        env:
-          REQUIREMENTS: docs/requirements.txt
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Deploy MkDocs website
+        run: |
+          mkdocs gh-deploy --force