Fix detected blocking call inside the event loop

aiobotocore/session.py

@@ -1,7 +1,11 @@
+import asyncio
+import functools
+
 from botocore import UNSIGNED
 from botocore import __version__ as botocore_version
 from botocore import translate
 from botocore.exceptions import PartialCredentialsError
+from botocore.loaders import Loader
 from botocore.session import EVENT_ALIASES, ServiceModel
 from botocore.session import Session as _SyncSession
 from botocore.session import UnknownServiceError, copy
@@ -103,9 +107,11 @@ async def get_service_data(self, service_name, api_version=None):
         Retrieve the fully merged data associated with a service.
         """
         data_path = service_name
-        service_data = self.get_component('data_loader').load_service_model(
+        data_loader: Loader = self.get_component('data_loader')
+        loop = asyncio.get_event_loop()
+        service_data = await loop.run_in_executor(None, functools.partial(data_loader.load_service_model,
             data_path, type_name='service-2', api_version=api_version
-        )
+        ))
         service_id = EVENT_ALIASES.get(service_name, service_name)
         await self._events.emit(
             'service-data-loaded.%s' % service_id,