test: unpin responses (#11768)

### Summary & Motivation
See what happens. I want to use the modern API.

### How I Tested These Changes
bk

python_modules/dagster/setup.py

@@ -162,7 +162,7 @@ def _get_grpcio_requires():
             "pytest-runner==5.2",
             "pytest-xdist==2.1.0",
             "pytest==7.0.1",  # last version supporting python 3.6
-            "responses==0.10.*",
+            "responses",
             "snapshottest==0.6.0",
             "tox==3.25.0",
             "yamllint",