Replace Travis CI with GitHub Actions (#12)

.github/workflows/build.yml

@@ -0,0 +1,20 @@
+name: build
+on: [push, pull_request]
+
+jobs:
+  luacheck:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Install dependencies
+      run: |
+        sudo apt-get update -qq
+        sudo apt-get install -qqq luarocks
+    - name: Install LuaCheck and pre-commit
+      run: |
+        pip3 install pre-commit
+        luarocks install --local luacheck
+    - name: Run LuaCheck with pre-commit
+      run: |
+        export PATH="$HOME/.luarocks/bin:$PATH"
+        pre-commit run --all-files