python: test with more modern versions (#19452)

Python 3.12 has been released in October 2023, it should be tested in
the CI.

Python 3.7 is not maintained anymore, removing it from the minimum
required version in `pyproject.toml` files.

samples/client/echo_api/python/.github/workflows/python.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
 
     steps:
       - uses: actions/checkout@v3

samples/client/echo_api/python/pyproject.toml

@@ -10,7 +10,7 @@ keywords = ["OpenAPI", "OpenAPI-Generator", "Echo Server API"]
 include = ["openapi_client/py.typed"]
 
 [tool.poetry.dependencies]
-python = "^3.7"
+python = "^3.8"
 
 urllib3 = ">= 1.25.3"
 python-dateutil = ">=2.8.2"
@@ -22,7 +22,7 @@ pytest = ">=7.2.1"
 tox = ">=3.9.0"
 flake8 = ">=4.0.0"
 types-python-dateutil = ">=2.8.19.14"
-mypy = "1.4.1"
+mypy = ">=1.5"
 
 
 [build-system]