Backport PR pandas-dev#35621: CI: Linux py36_locale failures with pytest DeprecationWarning

Author: simonjayhawkins

ci/deps/azure-36-locale.yaml

@@ -7,7 +7,7 @@ dependencies:
 
   # tools
   - cython>=0.29.16
-  - pytest>=5.0.1
+  - pytest>=5.0.1,<6.0.0  # https://github.com/pandas-dev/pandas/issues/35620
   - pytest-xdist>=1.21
   - pytest-asyncio
   - hypothesis>=3.58.0