Add support of Pytest 9.x (#35)

Update tox configuration:
- Reduce test matrix to the latest release from each major pytest version
- Add pytest main

Author: yugokato

pyproject.toml

@@ -28,7 +28,7 @@ classifiers = [
   "Topic :: Software Development :: Testing",
 ]
 dependencies = [
-    "pytest>=7.0.0,<9",
+    "pytest>=7.0.0,<10",
     "pluggy>=1.2.0",
     'typing_extensions>=4.1.0; python_version < "3.11"'
 ]

tox.ini

@@ -1,27 +1,21 @@
 [tox]
 env_list =
-    py310-pytest{7.0,7.1,7.2,7.3,7.4,8.0,8.1,8.2,8.3,8.4}
-    py311-pytest{7.2,7.3,7.4,8.0,8.1,8.2,8.3,8.4}
-    py312-pytest{7.3,7.4,8.0,8.1,8.2,8.3,8.4}
-    py313-pytest{8.2,8.3,8.4}
-    py314-pytest{8.4}
+    py310-pytest{7,8,9,main}
+    py311-pytest{7,8,9,main}
+    py312-pytest{7,8,9,main}
+    py313-pytest{8,9,main}
+    py314-pytest{8,9,main}
     linting
 
 [testenv]
 package = wheel
 wheel_build_env = .pkg
 extras = test
 deps =
-    pytest8.4: pytest~=8.4.0
-    pytest8.3: pytest~=8.3.0
-    pytest8.2: pytest~=8.2.0
-    pytest8.1: pytest~=8.1.0
-    pytest8.0: pytest~=8.0.0
-    pytest7.4: pytest~=7.4.0
-    pytest7.3: pytest~=7.3.0
-    pytest7.2: pytest~=7.2.0
-    pytest7.1: pytest~=7.1.0
-    pytest7.0: pytest~=7.0.0
+    pytestmain: git+https://github.com/pytest-dev/pytest.git
+    pytest9: pytest~=9.0
+    pytest8: pytest~=8.0
+    pytest7: pytest~=7.0
 commands =
     pytest tests {posargs:-n auto}