Backport PR matplotlib#31896: TST: temporarily pin pytest

Author: timhoffm

environment.yml

@@ -63,7 +63,7 @@ dependencies:
   - psutil
   - prek
   - pydocstyle>=5.1.0
-  - pytest!=4.6.0,!=5.4.0,!=8.1.0
+  - pytest!=4.6.0,!=5.4.0,!=8.1.0,<9.1.0
   - pytest-cov
   - pytest-rerunfailures
   - pytest-timeout

pyproject.toml

@@ -130,7 +130,7 @@ test = [
     "certifi",
     "coverage!=6.3",
     "psutil; sys_platform != 'cygwin'",
-    "pytest!=4.6.0,!=5.4.0,!=8.1.0",
+    "pytest!=4.6.0,!=5.4.0,!=8.1.0,<9.1.0",
     "pytest-cov",
     "pytest-rerunfailures!=16.0",
     "pytest-timeout",