👷 Fix Material for MkDocs install in CI (#395)

.github/workflows/build-docs.yml

@@ -34,25 +34,25 @@ jobs:
         id: cache
         with:
           path: ${{ env.pythonLocation }}
-          key: ${{ runner.os }}-python-${{ env.pythonLocation }}-${{ hashFiles('pyproject.toml') }}-docs
+          key: ${{ runner.os }}-python-docs-${{ env.pythonLocation }}-${{ hashFiles('pyproject.toml') }}-v01
       - name: Install Flit
         if: steps.cache.outputs.cache-hit != 'true'
         run: python3.7 -m pip install flit
       - name: Install docs extras
         if: steps.cache.outputs.cache-hit != 'true'
         run: python3.7 -m flit install --extras doc
       - name: Install Material for MkDocs Insiders
-        if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.fork == false && steps.cache.outputs.cache-hit != 'true'
+        if: ( github.event_name != 'pull_request' || github.event.pull_request.head.repo.fork == false ) && steps.cache.outputs.cache-hit != 'true'
         run: python3.7 -m pip install git+https://${{ secrets.ACTIONS_TOKEN }}@github.com/squidfunk/mkdocs-material-insiders.git
       - uses: actions/cache@v2
         with:
           key: mkdocs-cards-${{ github.ref }}-v1
           path: .cache
       - name: Build Docs
-        if: github.event.pull_request.head.repo.fork == true
+        if: github.event_name == 'pull_request' && github.event.pull_request.head.repo.fork == true
         run: python3.7 -m mkdocs build
       - name: Build Docs with Insiders
-        if: github.event.pull_request.head.repo.fork == false
+        if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.fork == false
         run: python3.7 -m mkdocs build --config-file mkdocs.insiders.yml
       - name: Zip docs
         run: bash ./scripts/zip-docs.sh