Revert "feat: upgrade to node 24"

This reverts commit c4cd38db20.

action.yml

@@ -49,5 +49,5 @@ outputs:
   ruby-prefix:
     description: 'The prefix of the installed ruby'
 runs:
-  using: 'node24'
+  using: 'node20'
   main: 'dist/index.js'

package.json

@@ -3,9 +3,6 @@
   "version": "0.1.0",
   "description": "Download a prebuilt Ruby and add it to the PATH in 5 seconds",
   "main": "index.js",
-  "engines": {
-    "node": ">=24.0.0"
-  },
   "license": "MIT",
   "scripts": {
     "package": "ncc build index.js -o dist"