Drop support for Python before 3.9

built-in zoneinfo is too good to work around

.github/workflows/test.yml

@@ -17,13 +17,9 @@ jobs:
     strategy:
       matrix:
         python-version:
-        - '3.7'
-        - '3.8'
         - '3.9'
         - '3.10'
         - '3.11.0-rc.1 - 3.11'
-        - 'pypy-3.7'
-        - 'pypy-3.8'
         - 'pypy-3.9'
         os-version:
         - 'ubuntu-latest'

requirements-dev.txt

@@ -16,6 +16,5 @@ twine; implementation_name=="cpython"
 types-beautifulsoup4
 types-python-dateutil
 types-requests
-backports.zoneinfo; python_version<"3.9"
 tzdata
 wheel

src/wwvb/tz.py

@@ -6,16 +6,7 @@
 #
 # SPDX-License-Identifier: GPL-3.0-only
 
-import datetime
-import sys
-from typing import Callable
-
-ZoneInfo: Callable[[str], datetime.tzinfo]
-
-if sys.version_info >= (3, 9):  # pragma no coverage
-    from zoneinfo import ZoneInfo
-else:  # pragma no coverage
-    from backports.zoneinfo import ZoneInfo
+from zoneinfo import ZoneInfo
 
 Mountain = ZoneInfo("America/Denver")