Limiting yarl dependency version to be compatible with python 3.7 (when min version suported >= 3.8 this constraint can be removed) (#1507)

Author: axelsrz

libraries/botbuilder-integration-aiohttp/setup.py

@@ -9,6 +9,7 @@
     "botbuilder-schema==4.12.0",
     "botframework-connector==4.12.0",
     "botbuilder-core==4.12.0",
+    "yarl<=1.4.2",
     "aiohttp==3.6.2",
 ]