Updated github precommit workflow to install pydoc-markdown

.github/workflows/pre-commit.yml

       with:
         dotnet-version: '3.1.x'
     - uses: pre-commit/action@v2.0.0
+    - name: Install dependencies
+      run: |
+          python -m pip install --upgrade pip
+          pip install pydoc-markdown
 
   markdown-link-check:
     runs-on: ubuntu-latest