ref(pydantic-ai): Fix type annotation style in execute_tool_span

Move Optional inside quotes for consistency with type annotation
style conventions.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: ericapisani

sentry_sdk/integrations/pydantic_ai/spans/execute_tool.py

@@ -17,7 +17,7 @@ def execute_tool_span(
     tool_args: "Any",
     agent: "Any",
     tool_type: str = "function",
-    tool_definition: Optional["ToolDefinition"] = None,
+    tool_definition: "Optional[ToolDefinition]" = None,
 ) -> "sentry_sdk.tracing.Span":
     """Create a span for tool execution.