Fix route discovery on starlette < 0.20.1

starlette._utils.is_async_callable was introduced in 0.20.1. On older
versions (e.g. 0.16.0 used by FastAPI 0.70.0) the ImportError caused
an early return, skipping the post_response handler entirely. This
meant routes were never recorded in heartbeats.

Fall back to inspect.iscoroutinefunction when _utils is unavailable.

Author: hansott

aikido_zen/sources/starlette/starlette_routing.py

@@ -45,10 +45,16 @@ async def aikido_route_func(*args, **kwargs):
         try:
             import functools
             from starlette.concurrency import run_in_threadpool
-            from starlette._utils import is_async_callable
         except ImportError:
-            logger.info("Make sure starlette install OK : .concurrency, ._utils")
+            logger.info("Make sure starlette install OK : .concurrency")
             return await func(*args, **kwargs)
+        try:
+            from starlette._utils import is_async_callable
+        except ImportError:
+            # starlette < 0.20.1 doesn't have _utils.is_async_callable
+            import inspect
+
+            is_async_callable = inspect.iscoroutinefunction
         res = None
         if is_async_callable(func):
             res = await func(*args, **kwargs)