feat: drop support for and testing on Python 3.8

.github/workflows/python-package.yml

@@ -88,7 +88,6 @@ jobs:
           - windows-latest
           - macos-latest
         python-version:
-          - '3.8'
           - '3.9'
           - '3.10'
           - '3.11'
@@ -105,7 +104,7 @@ jobs:
             python-version: '3.13-dev'
         include:
           - os: ubuntu-latest
-            python-version: '3.8'
+            python-version: '3.9'
             constraints: '--constraint constraints-oldest.txt'
           - os: ubuntu-latest
             python-version: '3.12'

pyproject.toml

@@ -6,7 +6,7 @@ requires = ["setuptools", "wheel"]  # PEP 508 specifications.
 # Darker makes Black read its configuration from the file indicated by the `--config`
 # option, so we need to mirror the same configuration here and in `check-darker.toml`.
 skip-string-normalization = false
-target-version = ["py38", "py39", "py310", "py311", "py312"]
+target-version = ["py39", "py310", "py311", "py312"]
 
 [tool.isort]
 # Darker makes isort read its configuration from the file indicated by the `--config`

setup.cfg

@@ -10,7 +10,6 @@ description = Apply Black formatting only in regions changed since last commit
 long_description_content_type = text/x-rst
 classifiers =
     Programming Language :: Python :: 3 :: Only
-    Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
     Programming Language :: Python :: 3.10
     Programming Language :: Python :: 3.11
@@ -33,7 +32,7 @@ install_requires =
     typing_extensions>=4.0.1
 # NOTE: remember to keep `.github/workflows/python-package.yml` in sync
 #       with the minimum required Python version
-python_requires = >=3.8
+python_requires = >=3.9
 
 [options.packages.find]
 where = src