Added action for running tests

.github/workflows/run-tests.yml

@@ -0,0 +1,33 @@
+# This is a basic workflow to help you get started with Actions
+
+name: Run tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        python-version: [3.6, 3.7, 3.8, 3.9]
+        os: [ubuntu-latest, windows-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+        with:
+          submodules: recursive
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install pyebur128
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install .[tests]
+      - name: Test with pytest
+        run: |
+          python -m pytest