replace travis with github action

the github action builds a release and uploads it to github releases

.github/workflows/release.yml

@@ -0,0 +1,43 @@
+name: Make a release
+
+on:
+  push:
+    # Sequence of patterns matched against refs/tags
+    tags:
+      - 'v*' # Push events to matching v*, i.e. v1.0, v20.15.10
+
+jobs:
+  release:
+    runs-on: ubuntu-18.04
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Set up Python 3.7
+      uses: actions/setup-python@v1
+      with:
+        python-version: 3.7
+
+    - name: Install pypa/build
+      run: >-
+        python -m
+        pip install
+        build
+        --user
+
+    - name: Build a binary wheel and a source tarball
+      run: >-
+        python -m
+        build
+        --sdist
+        --wheel
+        --outdir dist/
+        .
+
+    - name: Create a github release
+      uses: softprops/action-gh-release@v1
+      if: startsWith(github.ref, 'refs/tags/')
+      with:
+        prerelease: true
+        files: dist/*
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}