build: Python 3.6 is the minimum

Author: Ned Batchelder

Makefile

@@ -24,7 +24,7 @@ clean: ## remove generated byte code, coverage reports, and build artifacts
 	cd docs; make clean
 
 coverage: clean ## generate and view HTML coverage report
-	tox -e py35,py38,coverage
+	tox -e py36,py39,coverage
 	$(BROWSER)htmlcov/index.html
 
 docs: ## generate Sphinx HTML documentation, including API docs

changelog.d/20210622_071634_nedbat_no_travis.rst

@@ -0,0 +1,5 @@
+Changed
+.......
+
+- Python 3.6 is now the minimum supported Python version.
+

setup.cfg

@@ -15,6 +15,10 @@ classifiers =
     License :: OSI Approved :: Apache Software License
     Natural Language :: English
     Programming Language :: Python :: 3
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
 
 [options]
 packages =
@@ -74,7 +78,7 @@ source =
     */site-packages
 
 [mypy]
-python_version = 3.5
+python_version = 3.6
 ignore_missing_imports = True
 check_untyped_defs = True
 

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py35,py36,py37,py38,py39,pypy3,coverage,docs,quality
+envlist = py36,py37,py38,py39,pypy3,coverage,docs,quality
 
 [testenv]
 deps =
@@ -16,14 +16,14 @@ commands =
     coverage run -p -m pytest -Wd {posargs}
 
 [testenv:coverage]
-envdir = {toxworkdir}/py38
+envdir = {toxworkdir}/py36
 commands =
     coverage combine
     coverage report -m --skip-covered
     coverage html
 
 [testenv:docs]
-basepython = python3.8
+basepython = python3.6
 setenv =
     PYTHONPATH = {toxinidir}
 deps =
@@ -35,7 +35,7 @@ commands =
     doc8 -q --ignore-path docs/include README.rst docs
 
 [testenv:quality]
-basepython = python3.8
+basepython = python3.6
 deps =
     -r{toxinidir}/requirements/quality.txt
 commands =
@@ -49,16 +49,13 @@ commands =
     twine check dist/*
 
 [testenv:upgrade]
-# Picking a version to pin in is tricky. Use a late version, and pin packages
-# in constraints.txt to keep them working on the earlier versions.
-basepython = python3.8
+basepython = python3.6
 commands =
     python -m pip install -U pip
     make upgrade
 
 [gh-actions]
 python =
-    3.5: py35
     3.6: py36
     3.7: py37
     3.8: py38