Update mcp-server-diff action to v2.2.0

Updates to v2.2.0 which includes server instructions diff support for
detecting issues like #1897.

Author: SamMorrowDrums

.github/workflows/mcp-diff.yml

@@ -20,7 +20,7 @@ jobs:
           fetch-depth: 0
 
       - name: Run MCP Server Diff
-        uses: SamMorrowDrums/mcp-server-diff@v2
+        uses: SamMorrowDrums/mcp-server-diff@v2.2.0
         with:
           setup_go: "true"
           install_command: go mod download