simpler sniffio vcs pin

Author: altendky

setup.cfg

@@ -93,7 +93,7 @@ contextvars =
     contextvars >= 2.4, < 3; python_version < "3.7"
 
 sniffio =
-    sniffio >= 1.1, <2 @ git+https://github.com/python-trio/sniffio@twisted
+    sniffio @ git+https://github.com/python-trio/sniffio@twisted
 
 all_non_platform =
     %(test)s