Display plugin name on uninitialized error

Signed-off-by: Emmanuel Ferdman <[email protected]>

Author: emmanuel-ferdman

mavsdk/system.py

@@ -168,7 +168,7 @@ async def _init_plugins(self, host, port):
 
     @staticmethod
     def error_uninitialized(plugin_name: str) -> str:
-        return "{plugin_name} plugin has not been initialized! " \
+        return f"{plugin_name} plugin has not been initialized! " \
             "Did you run `System.connect()`?"
 
     @property