CI: Run on GitHub Actions

We have Zuul, and we're happy with it; however, every now and then
there's a problem with the managed infrastructure, and there's also
people who contribute patches as GitHub PRs.

Change-Id: I405c5806ed9ad2e7f59f9b2394daf068b373e425

.github/workflows/main.yml

@@ -0,0 +1,27 @@
+on:
+  create:
+  push:
+  pull_request:
+    branches:
+      - master
+
+name: build
+
+jobs:
+  build:
+    name: Tox test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: fedora-python/tox-github-action@v0.4
+        with:
+          tox_env: ${{ matrix.tox_env }}
+          dnf_install: ${{ matrix.dnf_install }}
+    strategy:
+      matrix:
+        tox_env:
+          - py38
+          - py39
+        include:
+          - tox_env: docs
+            dnf_install: graphviz

README.md

@@ -3,7 +3,7 @@
 [![Install via pip](https://img.shields.io/pypi/v/gnpy)](https://pypi.org/project/gnpy/)
 [![Python versions](https://img.shields.io/pypi/pyversions/gnpy)](https://pypi.org/project/gnpy/)
 [![Documentation status](https://readthedocs.org/projects/gnpy/badge/?version=master)](http://gnpy.readthedocs.io/en/master/?badge=master)
-[![CI](https://travis-ci.com/Telecominfraproject/oopt-gnpy.svg?branch=master)](https://travis-ci.com/Telecominfraproject/oopt-gnpy)
+[![GitHub Workflow Status](https://img.shields.io/github/workflow/status/Telecominfraproject/oopt-gnpy/build)](https://github.com/Telecominfraproject/oopt-gnpy/actions/workflows/main.yml)
 [![Gerrit](https://img.shields.io/badge/patches-via%20Gerrit-blue)](https://review.gerrithub.io/q/project:Telecominfraproject/oopt-gnpy+is:open)
 [![Contributors](https://img.shields.io/github/contributors-anon/Telecominfraproject/oopt-gnpy)](https://github.com/Telecominfraproject/oopt-gnpy/graphs/contributors)
 [![Code Quality via LGTM.com](https://img.shields.io/lgtm/grade/python/github/Telecominfraproject/oopt-gnpy)](https://lgtm.com/projects/g/Telecominfraproject/oopt-gnpy/)