Allow testing with pytest 9

pytest 9 was recently released. This change allows it to be used in
testing with tox.

Author: diazona

tox.ini

@@ -22,9 +22,9 @@ deps =
     # works with your code. Don't forget to modify the corresponding entries in
     # the Github workflows configuration file if you do change these lower
     # bounds.
-    pytest >=4.6, <9; python_version <'3.10'
-    pytest >=6.2.4, <9; python_version >='3.10' and python_version <'3.14'
-    pytest >=7.3.2, <9; python_version >='3.14'
+    pytest >=4.6, <10; python_version <'3.10'
+    pytest >=6.2.4, <10; python_version >='3.10' and python_version <'3.14'
+    pytest >=7.3.2, <10; python_version >='3.14'
     pytest-cov !=6.2.0
     requests
 extras =