Drop support for Python 3.8

Note that recent commits introduced syntax unsupported by Python 3.8
already.

CHANGELOG.rst

@@ -14,6 +14,7 @@ Version 0.21.0
 
 - Implement retrying for ``google`` storage type when a rate limit is reached.
 - ``tenacity`` is now a required dependency.
+- Drop support for Python 3.8.
 
 Version 0.20.0
 ==============

docs/installation.rst

@@ -42,7 +42,7 @@ If your distribution doesn't provide a package for vdirsyncer, you still can
 use Python's package manager "pip". First, you'll have to check that the
 following things are installed:
 
-- Python 3.8 to 3.13 and pip.
+- Python 3.9 to 3.13 and pip.
 - ``libxml`` and ``libxslt``
 - ``zlib``
 - Linux or macOS. **Windows is not supported**, see :gh:`535`.

pyproject.toml

@@ -14,7 +14,7 @@ authors = [
 ]
 description = "Synchronize calendars and contacts"
 readme = "README.rst"
-requires-python = ">=3.8"
+requires-python = ">=3.9"
 keywords = ["todo", "task", "icalendar", "cli"]
 license = "BSD-3-Clause"
 license-files = ["LICENSE"]
@@ -27,7 +27,6 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Topic :: Internet",
     "Topic :: Office/Business :: Scheduling",

vdirsyncer/__init__.py

@@ -23,8 +23,8 @@ __all__ = ["__version__"]
 def _check_python_version():
     import sys
 
-    if sys.version_info < (3, 8, 0):  # noqa: UP036
-        print("vdirsyncer requires at least Python 3.8.")
+    if sys.version_info < (3, 9, 0):  # noqa: UP036
+        print("vdirsyncer requires at least Python 3.9.")
         sys.exit(1)