[deps] DevOps: Update mcr.microsoft.com/devcontainers/dotnet Docker tag to v9

Author: renovate[bot]

.devcontainer/bitwarden_common/docker-compose.yml

@@ -2,7 +2,7 @@ version: '3'
 
 services:
   bitwarden_server:
-    image: mcr.microsoft.com/devcontainers/dotnet:8.0
+    image: mcr.microsoft.com/devcontainers/dotnet:9.0
     volumes:
       - ../../:/workspace:cached
     # Overrides default command so things don't shut down after the process ends.