added mypy static analyzer action on push

.github/workflows/python-mypy.yml

@@ -0,0 +1,21 @@
+name: Mypy
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    name: Mypy
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.x'
+    - name: Install Dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install mypy
+    - name: mypy
+      run: |
+        mypy pydualsense/