MAINT: Set up github actions

.github/workflows/unit_tests.yml

@@ -0,0 +1,43 @@
+name: Python package
+
+on:
+  push:
+    branches: ['**']
+  pull_request:
+    branches: ['**']
+  create:
+    branches: [main]
+    tags: ['**']
+  schedule:
+    - cron: "0 4 * * *"
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [3.6, 3.7, 3.8]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install flake8 pytest
+
+    - name: Install HNN
+      run: |
+        python setup.py install
+
+    - name: Lint with flake8
+      run: |
+        flake8 --count hnn_core
+    - name: Test with pytest
+      run: |
+        python -m py.test .  --cov=hnn_core hnn_core/tests/ --cov-report=xml