chore: update Node.js version in the conformance action to 22 (#162)

With Node.js 20 the action fails with:

```
SyntaxError: The requested module 'fs' does not provide an export named 'globSync'
    at ModuleJob._instantiate (node:internal/modules/esm/module_job:213:21)
    at async ModuleJob.run (node:internal/modules/esm/module_job:320:5)
    at async ModuleLoader.import (node:internal/modules/esm/loader:606:24)
    at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:117:5)
```

`fs.globSync` was added in Node.js 22.

action.yml

@@ -28,9 +28,9 @@ inputs:
     required: false
     default: 'false'
   node-version:
-    description: 'Node.js version to use (default: 20)'
+    description: 'Node.js version to use (default: 22)'
     required: false
-    default: '20'
+    default: '22'
 runs:
   using: 'composite'
   steps: