fix: use ghcr mirror by default (#113)

src/main.ts

@@ -16,6 +16,9 @@ async function run(): Promise<void> {
 
     // Expose the tool by adding it to the PATH
     core.addPath(pathToCLI)
+
+    // Use GHCR mirror by default
+    core.exportVariable('SUPABASE_INTERNAL_IMAGE_REGISTRY', 'ghcr.io')
   } catch (error) {
     if (error instanceof Error) core.setFailed(error.message)
   }