Fix doc code formatting.

Author: sstanovnik

docs/logfire.md

@@ -383,6 +383,7 @@ Alternatively, supply a callable that receives the run [`RunContext`][pydantic_a
 from pydantic_ai import Agent, RunContext
 from pydantic_ai.models.instrumented import InstrumentationSettings
 
+
 def span_attribute_callback(ctx: RunContext[None]) -> dict[str, str]:
     return {'my_org.prompt_preview': str(ctx.prompt)[:100]}