chore: fixing version of icons

Signed-off-by: benjdlambert <ben@blam.sh>

packages/create-app/templates/next-app/packages/app/package.json.hbs

@@ -25,7 +25,7 @@
     "@backstage/core-components": "^{{ version '@backstage/core-components'}}",
     "@backstage/ui": "^{{ version '@backstage/ui'}}",
     "@material-ui/core": "^4.12.2",
-    "@material-ui/icons": "^5.11.11",
+    "@material-ui/icons": "^4.9.1",
     "react": "^18.0.2",
     "react-dom": "^18.0.2",
     "react-router": "^6.3.0",