ci: add GitHub Actions workflow for tests (#15)

Author: dlyongemallo

.github/workflows/ci.yml

@@ -0,0 +1,26 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        neovim: [stable, nightly]
+    name: Test (Neovim ${{ matrix.neovim }})
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: rhysd/action-setup-vim@v1
+        with:
+          neovim: true
+          version: ${{ matrix.neovim }}
+
+      - name: Run tests
+        run: make test