switch from Travis to GH actions

Author: pawelmhm

.github/workflows/main.yml

@@ -0,0 +1,30 @@
+name: Run tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix: 
+        python-version: ["3.6", "3.7", "3.8", "3.9"]
+    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 -r requirements.txt
+        pip install -r requirements-test.txt
+    - name: Run tests
+      run: |
+        pytest