Upgrade pnpm v8 -> v9 (#198)

Author: bvaughn

.github/workflows/ci.yml

@@ -14,7 +14,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
         with:
-          version: 8.6.10
+          version: 9.6.0
       - uses: actions/setup-node@v4
         with:
           cache: "pnpm"

package.json

@@ -4,11 +4,14 @@
   "description": "Simple reusable React error boundary component",
   "author": "Brian Vaughn <brian.david.vaughn@gmail.com>",
   "license": "MIT",
-  "packageManager": "pnpm@8.6.10",
   "repository": {
     "type": "git",
     "url": "https://github.com/bvaughn/react-error-boundary"
   },
+  "engines": {
+    "node": ">=20",
+    "pnpm": "=9"
+  },
   "main": "dist/react-error-boundary.cjs.js",
   "module": "dist/react-error-boundary.esm.js",
   "exports": {