Update test.yml

Author: varndellwagglebee

.github/workflows/test.yml

@@ -17,7 +17,7 @@ on:
 env:
   BRANCH_NAME: ${{ github.head_ref || github.ref_name }}
   SOLUTION_NAME: ${{ vars.SOLUTION_NAME }}
-  DOTNET_VERSION: '8.0.x'
+  DOTNET_VERSION: '9.0.x'
 
 jobs:
   test: