Add explicit permissions to check-dotnet10 workflow for security

Co-authored-by: softworkz <4985349+softworkz@users.noreply.github.com>

Author: Copilot

.github/workflows/check-dotnet10.yml

@@ -11,6 +11,8 @@ on:
 jobs:
   check-dotnet10-ubuntu:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
 
     steps:
     - name: Check pre-installed .NET versions