added openpyxl installation to docs-check GitHub action

.github/workflows/docs-check.yml

@@ -1,21 +1,21 @@
-name: "Docs Check"
-on: pull_request
-
-jobs:
-  docs:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2.3.4
-    - name: Set up Python
-      uses: actions/setup-python@v2
-      with:
-          python-version: '3.x'
-    - name: Install Sphinx
-      run: |
-        python -m pip install --upgrade pip
-        pip install sphinx sphinx_rtd_theme
-    - name: Move to docs folder and build
-      run: |
-        cd doc
-        pwd
-        sphinx-build -T -E -W -b html . _build
+name: "Docs Check"
+on: pull_request
+
+jobs:
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2.3.4
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+      - name: Install Sphinx
+        run: |
+          python -m pip install --upgrade pip
+          pip install sphinx sphinx_rtd_theme openpyxl
+      - name: Move to docs folder and build
+        run: |
+          cd doc
+          pwd
+          sphinx-build -T -E -W -b html . _build