Fix JSON syntax error in diagram.json - remove trailing comma

- Remove trailing comma after last element in connections array (line 17)
- Trailing commas are not valid in JSON
- Fixes "SyntaxError: Unexpected token ']'" error from Wokwi CLI
- JSON is now valid and should parse correctly

Co-authored-by: softhack007 <[email protected]>

Author: Copilot

test/wokwi/diagram.json

@@ -13,7 +13,7 @@
   ],
   "connections": [
     [ "esp:TX0", "$serialMonitor:RX", "", [] ],
-    [ "esp:RX0", "$serialMonitor:TX", "", [] ],
+    [ "esp:RX0", "$serialMonitor:TX", "", [] ]
   ],
   "dependencies": {},
   "serialMonitor": {