Gate anyio version

Author: afshin

setup.cfg

@@ -42,7 +42,7 @@ install_requires =
     terminado>=0.8.3
     prometheus_client
     pywin32>=1.0 ; sys_platform == 'win32'
-    anyio>=2.0.2
+    anyio>=2.0.2,<3
 
 [options.extras_require]
 test = coverage; pytest; pytest-cov; pytest-mock; requests; pytest-tornasync; pytest-console-scripts; ipykernel