fix: add type hint to set variable

Author: fubuloubu

src/mcp/server/fastmcp/server.py

@@ -381,7 +381,7 @@ def decorator(fn: AnyFunction) -> AnyFunction:
 
                 # Get all function params except 'ctx' or any parameter of type Context
                 sig = inspect.signature(fn)
-                func_params = set()
+                func_params: set[str] = set()
                 for param_name, param in sig.parameters.items():
                     # Skip context parameters
                     if param_name == "ctx" or (