chore: upgrade to yarn v4

.gitignore

@@ -35,3 +35,4 @@ log.html
 
 # Swift build folder
 .build
+.yarn/install-state.gz

.yarnrc.yml

@@ -0,0 +1 @@
+yarnPath: .yarn/releases/yarn-4.2.1.cjs

package.json

@@ -5,16 +5,18 @@
   "private": true,
   "scripts": {
     "generate": "tree-sitter generate --no-bindings",
+    "build": "yarn generate",
     "test": "tree-sitter test",
     "lint": "eslint grammar.js && prettier --check grammar.js",
     "format": "prettier --write grammar.js",
     "test:debug": "tree-sitter test --debug",
-    "postinstall": "yarn generate"
+    "postinstall": "Echo 'yarn generate'"
   },
   "devDependencies": {
     "eslint": "^8.25.0",
     "eslint-plugin-tree-sitter": "^0.0.1",
     "prettier": "^2.7.1",
     "tree-sitter-cli": "0.20.7"
-  }
+  },
+  "packageManager": "yarn@4.2.1"
 }