Add initial GA workflow

.github/workflows/build.yml

@@ -0,0 +1,39 @@
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  test:
+    runs-on: ${{ matrix.operating-system }}
+    strategy:
+      fail-fast: true
+      matrix:
+        operating-system: [ ubuntu-latest, macos-latest, windows-latest ]
+        php: [ '5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0' ]
+        dependencies: [ 'lowest', 'locked' ]
+
+    name: PHP ${{ matrix.php }} on ${{ matrix.operating-system }} with ${{ matrix.dependencies }} dependencies
+
+    steps:
+      - uses: actions/checkout@v2
+        name: Checkout repository
+
+      - name: Setup PHP
+        uses: nanasess/setup-php@master
+        with:
+          php-version: ${{ matrix.php }}
+
+      - uses: ramsey/composer-install@v1
+        with:
+          dependency-versions: ${{ matrix.dependencies }}
+          composer-options: ${{ matrix.composer-options }}
+
+      - name: Run tests
+        working-directory: test
+        run: |
+          pear install -f package.xml
+          pear version
+          pear run-tests -qr tests/
+          for i in `find tests/ -name '*.out'`; do echo "$i"; cat "$i"; done