add dotnet-format to tool manifest

Author: matracey

.config/dotnet-tools.json

@@ -1,5 +1,10 @@
 {
   "version": 1,
   "isRoot": true,
-  "tools": {}
+  "tools": {
+    "dotnet-format": {
+      "version": "5.1.250801",
+      "commands": ["dotnet-format"]
+    }
+  }
 }