fix(ci): Configure Renovate for Forgejo platform

- Set platform to 'forgejo' with proper API endpoint
- Use environment variables for all Renovate configuration
- Add git timeout and disable GitHub token warnings
- Move PR limit configuration to workflow

renovate.json

@@ -58,7 +58,5 @@
       "matchUpdateTypes": ["patch"],
       "groupName": "rust-patch-updates"
     }
-  ],
-  "prConcurrentLimit": 3,
-  "prHourlyLimit": 2
+  ]
 }