github: Run continuous integration tests using "github actions"

Use "github actions" instead of "travis ci" for the automatic build
regression tests.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

.github/workflows/build-test.yaml

@@ -0,0 +1,30 @@
+# Perform continuous integration tests on updates and pull requests
+name: Build test
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-18.04
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Install system dependencies
+      run: sudo apt-get install gcc-avr avr-libc pv libmpfr-dev libgmp-dev libmpc-dev texinfo libncurses5-dev bison flex python-virtualenv virtualenv python-dev libffi-dev build-essential
+
+    - name: Setup cache
+      uses: actions/cache@v2
+      with:
+        path: travis_cache
+        key: ${{ runner.os }}-build-${{ hashFiles('scripts/travis-install.sh') }}
+
+    - name: Prepare tests
+      run: ./scripts/travis-install.sh
+
+    - name: Test
+      run: ./scripts/travis-build.sh 2>&1
+
+    - name: Upload micro-controller data dictionaries
+      uses: actions/upload-artifact@v2
+      with:
+        name: data-dict
+        path: travis_build/dict