Disable cache-cleanup on Windows

It does not seem possible to use `find .. -exec ..` on Windows,
so a node-only solution may be required.

src/cache-utils.ts

@@ -48,7 +48,14 @@ export function isCacheDebuggingEnabled(): boolean {
 }
 
 export function isCacheCleanupEnabled(): boolean {
-    return core.getBooleanInput(CACHE_CLEANUP_ENABLED_PARAMETER)
+    const userEnabled = core.getBooleanInput(CACHE_CLEANUP_ENABLED_PARAMETER)
+
+    if (userEnabled && process.platform === 'win32') {
+        core.warning('Cache cleanup is not yet supported on Windows')
+        return false
+    }
+
+    return userEnabled
 }
 
 /**