tox: drop py37-environment tests

Dropping various Python 3.7 targets in the tox configuration, which are
no longer applicable for this project.

See CONTRIBUTING.rst for additional information.

Signed-off-by: James Knight <[email protected]>

tox.ini

@@ -2,15 +2,12 @@
 envlist =
     flake8
     pylint
-    py37-sphinx53
-    py38-sphinx{53,60,61,62,70,71}
-    py{39,310,311}-sphinx{53,60,61,62,70,71,72}
+    py38-sphinx{61,62,70,71}
+    py{39,310,311}-sphinx{61,62,70,71,72}
 
 [testenv]
 deps =
     -r{toxinidir}/requirements_dev.txt
-    sphinx53: sphinx>=5.3,<5.4
-    sphinx60: sphinx>=6.0,<6.1
     sphinx61: sphinx>=6.1,<6.2
     sphinx62: sphinx>=6.2,<6.3
     sphinx70: sphinx>=7.0,<7.1
@@ -32,21 +29,21 @@ commands =
     {envpython} -m coverage html
     {envpython} -m coverage report
 
-[testenv:{,py37-,py38-,py39-,py310-,py311-,py312-}develop]
+[testenv:{,py38-,py39-,py310-,py311-,py312-}develop]
 deps =
     git+https://github.com/sphinx-doc/sphinx.git@{env:SPHINX_VER:master}
     -r{toxinidir}/requirements_dev.txt
 pip_pre = true
 
-[testenv:{,py37-,py38-,py39-,py310-,py311-,py312-}interactive]
+[testenv:{,py38-,py39-,py310-,py311-,py312-}interactive]
 commands =
     {envpython} -m sphinxcontrib.confluencebuilder {posargs}
 passenv = *
 
-[testenv:{,py37-,py38-,py39-,py310-,py311-,py312-}prerelease]
+[testenv:{,py38-,py39-,py310-,py311-,py312-}prerelease]
 pip_pre = true
 
-[testenv:{,py37-,py38-,py39-,py310-,py311-,py312-}release]
+[testenv:{,py38-,py39-,py310-,py311-,py312-}release]
 usedevelop = false
 
 [testenv:flake8]
@@ -76,14 +73,14 @@ commands =
     sphinxcontrib \
     tests
 
-[testenv:{,py37-,py38-,py39-,py310-,py311-,py312-}sandbox]
+[testenv:{,py38-,py39-,py310-,py311-,py312-}sandbox]
 deps =
     -r{toxinidir}/sandbox/requirements.txt
 commands =
     {envpython} -m tests.test_sandbox {posargs}
 passenv = *
 
-[testenv:{,py37-,py38-,py39-,py310-,py311-,py312-}validation]
+[testenv:{,py38-,py39-,py310-,py311-,py312-}validation]
 deps = 
     {[testenv]deps}
     -r{toxinidir}/tests/validation-sets/requirements.txt