switched to pnpm from yarn

Author: Code-Hex

package.json

@@ -15,6 +15,7 @@
     "README.md"
   ],
   "scripts": {
+    "preinstall": "npx only-allow pnpm",
     "type-check": "tsc --noEmit",
     "type-check:yup": "tsc --strict --noEmit example/yup/schemas.ts",
     "type-check:zod": "tsc --strict --noEmit example/zod/schemas.ts",