Update .NET SDK version to 9.0.306

Bumps the required .NET SDK version in global.json from 9.0.301 to 9.0.306 to ensure builds use the latest feature release.

Author: Sergio0694

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "9.0.301",
+    "version": "9.0.306",
     "rollForward": "latestFeature",
     "allowPrerelease": false
   }