fix: Plugins were re-registering on every re-render (#1613)

- Forgot dependency array for `useEffect` hook

Author: mofojed

packages/dashboard-core-plugins/src/WidgetLoaderPlugin.tsx

@@ -151,7 +151,7 @@ export function WidgetLoaderPlugin(
     return () => {
       deregisterFns.forEach(deregister => deregister());
     };
-  });
+  }, [registerComponent, supportedTypes]);
 
   /**
    * Listen for panel open events so we know when to open a panel