feat!: drop Python 3.7 support

3.7 reached end-of-life on 2023-06-27. Copilot dropped 3.7 from the CI
matrix in #30 but left the rest of the metadata pointing at it.

- setup.py: drop the 3.7 classifier and bump `python_requires` to >=3.8
- pyproject.toml: bump black `target-version` to py38
- tox.ini: drop `py37` and `pypy37` envs and basepython entries
- README.rst: bump quick-start Python range to 3.8-3.14
- ci/templates/.appveyor.yml: bump the `check` env from Python 3.6 to 3.8
  to keep the floor consistent (template only, not currently rendered)

BREAKING CHANGE: Edify now requires Python 3.8 or newer.

1 files changed, 1 insertions, 2 deletions

diff --git a/setup.py b/setup.py
index 49cd13c..f615e10 100755
--- a/setup.py
+++ b/setup.py
@@ -46,7 +46,6 @@ setup(
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3 :: Only',
-        'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3.9',
         'Programming Language :: Python :: 3.10',
@@ -70,7 +69,7 @@ setup(
     keywords=[
         # eg: 'keyword1', 'keyword2', 'keyword3',
     ],
-    python_requires='>=3.7',
+    python_requires='>=3.8',
     install_requires=[
         # eg: 'aspectlib==1.1.1', 'six>=1.7',
     ],