release version 3.1.2 (#5800)

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "Flask"
-version = "3.1.2.dev"
+version = "3.1.2"
 description = "A simple framework for building complex web applications."
 readme = "README.md"
 license = "BSD-3-Clause"
@@ -19,11 +19,10 @@ classifiers = [
     "Topic :: Software Development :: Libraries :: Application Frameworks",
     "Typing :: Typed",
 ]
-requires-python = ">=3.9"
+requires-python = ">=3.10"
 dependencies = [
     "blinker>=1.9.0",
     "click>=8.1.3",
-    "importlib-metadata>=3.6.0; python_version < '3.10'",
     "itsdangerous>=2.2.0",
     "jinja2>=3.1.2",
     "markupsafe>=2.1.1",
@@ -58,7 +57,7 @@ pre-commit = [
 ]
 tests = [
     "asgiref",
-    "greenlet ; python_version < '3.11'",
+    "greenlet",
     "pytest",
     "python-dotenv",
 ]
@@ -126,7 +125,7 @@ exclude_also = [
 ]
 
 [tool.mypy]
-python_version = "3.9"
+python_version = "3.10"
 files = ["src", "tests/type_check"]
 show_error_codes = true
 pretty = true
@@ -142,7 +141,7 @@ module = [
 ignore_missing_imports = true
 
 [tool.pyright]
-pythonVersion = "3.9"
+pythonVersion = "3.10"
 include = ["src", "tests/type_check"]
 typeCheckingMode = "basic"
 
@@ -161,6 +160,9 @@ select = [
     "UP",  # pyupgrade
     "W",  # pycodestyle warning
 ]
+ignore = [
+    "UP038",  # keep isinstance tuple
+]
 
 [tool.ruff.lint.isort]
 force-single-line = true
@@ -168,7 +170,7 @@ order-by-type = false
 
 [tool.tox]
 env_list = [
-    "py3.13", "py3.12", "py3.11", "py3.10", "py3.9",
+    "py3.13", "py3.12", "py3.11", "py3.10",
     "pypy3.11",
     "tests-min", "tests-dev",
     "style",