Update README.md (#87)

Symfony UX bundle is now compatible with the version 4 (https://github.com/symfony/ux-chartjs/blob/2.x/CHANGELOG.md#2140)

Author: Surfoo

README.md

@@ -136,7 +136,7 @@ In addition, many plugins can be found on the [npm registry](https://www.npmjs.c
   2️⃣ ❕ ❕ | [nova-chartjs](https://github.com/coroo/nova-chartjs) | Laravel Nova
   2️⃣ 3️⃣ 4️⃣ | [quickchart](https://github.com/typpo/quickchart) | Web API for static charts
   2️⃣ ❕ ❕ | [wicked-charts](https://github.com/adessoAG/wicked-charts) | Wrapper for Java web apps
-  ❕ 3️⃣ ❕ | [symfony/ux-chartjs](https://github.com/symfony/ux-chartjs) | Symfony UX bundle
+  ❕ 3️⃣ 4️⃣ | [symfony/ux-chartjs](https://github.com/symfony/ux-chartjs) | Symfony UX bundle
 
 ## Tools