Init GitHub Actions (#46)

.github/workflows/ci.yml

@@ -0,0 +1,36 @@
+name: mgrid
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    name: CI build
+    runs-on: macos-latest
+
+    strategy:
+      matrix:
+        python-version: [3.7.1]
+        poetry-version: [1.1.4]
+
+    steps:
+    - uses: actions/checkout@master
+
+    - name: Install Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Install poetry
+      uses: snok/install-poetry@v1.1.1
+      with:
+        version: ${{ matrix.poetry-version }}
+
+    - name: Install dependencies
+      run: poetry install
+
+    - name: Check pre-commit
+      run: poetry run pre-commit install && poetry run pre-commit run --all-files