Update ci workflow

.github/workflows/ci.yaml

@@ -72,8 +72,8 @@ jobs:
           . venv/bin/activate
           pre-commit install --install-hooks
 
-  formatting:
-    name: Run pre-commit checks
+  pylint:
+    name: Run pylint check
     runs-on: ubuntu-latest
     needs: prepare-base
     steps:
@@ -114,6 +114,48 @@ jobs:
           pip install -e .
           pre-commit run pylint --all-files
 
+  mypy:
+    name: Run mypy check
+    runs-on: ubuntu-latest
+    needs: prepare-base
+    steps:
+      - name: Check out code from GitHub
+        uses: actions/checkout@v2.3.4
+      - name: Set up Python ${{ env.DEFAULT_PYTHON }}
+        id: python
+        uses: actions/setup-python@v2.2.2
+        with:
+          python-version: ${{ env.DEFAULT_PYTHON }}
+      - name: Restore Python virtual environment
+        id: cache-venv
+        uses: actions/cache@v2.1.6
+        with:
+          path: venv
+          key:
+            ${{ runner.os }}-${{ steps.python.outputs.python-version }}-${{
+            needs.prepare-base.outputs.python-key }}
+      - name: Fail job if Python cache restore failed
+        if: steps.cache-venv.outputs.cache-hit != 'true'
+        run: |
+          echo "Failed to restore Python venv from cache"
+          exit 1
+      - name: Restore pre-commit environment
+        id: cache-precommit
+        uses: actions/cache@v2.1.6
+        with:
+          path: ${{ env.PRE_COMMIT_CACHE }}
+          key: ${{ runner.os }}-${{ needs.prepare-base.outputs.pre-commit-key }}
+      - name: Fail job if pre-commit cache restore failed
+        if: steps.cache-precommit.outputs.cache-hit != 'true'
+        run: |
+          echo "Failed to restore pre-commit environment from cache"
+          exit 1
+      - name: Run formatting check
+        run: |
+          . venv/bin/activate
+          pip install -e .
+          pre-commit run mypy --all-files
+
   spelling:
     name: Run spelling checks
     runs-on: ubuntu-latest