style: enforce code formatting in CI

.github/workflows/main.yml

@@ -26,4 +26,5 @@ jobs:
         run: |
           npm install
           npm run build --if-present
+          npm run format:check
           npm test

.prettierignore

@@ -1,3 +1,9 @@
 *.d.ts
 test/data/
 /example
+
+# output files
+/main.js
+/lib/**/*.js
+/parsers/**/*.js
+/test/**/*.js

package.json

@@ -28,6 +28,7 @@
     "build": "npm run clean && tsc",
     "lint": "eslint --ext .ts .",
     "format": "prettier --write .",
+    "format:check": "prettier --check .",
     "clean": "tsc --build --clean",
     "prepare": "npm run build",
     "postpack": "npm run clean"