remove now-unused parts of the test matrix

This commit was sponsored by Jason Walker, Matt Campbell, Sergio Bost,
and my other patrons.  If you want to join them, you can support my
work at https://patreon.com/creatorglyph.

Author: glyph

tox.ini

@@ -2,7 +2,7 @@
 isolated_build = True
 envlist =
     lint, mypy
-    coverage-py{37,38,39,310,311,py3}-tw{212,221,current,trunk}
+    coverage-py{38,39,310,311,py3}-tw{212,221,current,trunk}
     coverage_combine
     coverage_report
     docs, docs-linkcheck
@@ -44,14 +44,12 @@ description = run tests
 basepython =
     .package: python3.11
     py: python
-    py37: python3.7
     py38: python3.8
     py39: python3.9
     py310: python3.10
     py311: python3.11
     py312: python3.12
     pypy3: pypy3
-    pypy38: pypy3.8
     pypy39: pypy3.9
 
 deps = {[default]deps}