"spfx-uifabric-themes" to "^0.9.0" to fix #1187

Fix #1187 by bumping "spfx-uifabric-themes" to "^0.9.0".  "spfx-uifabric-themes" @ "^0.9.0" removes dependencies that are not needed and that were causing npm audit with critical failure for GHSA-xvch-5gv4-984h.

Author: brianpmccullough

package.json

@@ -57,7 +57,7 @@
     "react-mentions": "^4.3.0",
     "react-quill": "1.3.5",
     "regexify-string": "^1.0.16",
-    "spfx-uifabric-themes": "^0.8.5"
+    "spfx-uifabric-themes": "^0.9.0"
   },
   "devDependencies": {
     "@microsoft/microsoft-graph-types": "^2.1.0",