drop tests with sphinx v4

tox.ini

@@ -10,18 +10,18 @@ env_list =
     package
     pre-commit-run
     py{312,311,310,39,38}
-    py{312,311,310,39,38}-with-sphinx{4,5,6,7}
+    py{312,311,310,39,38}-with-sphinx{5,6,7}
     py{312,311,310,39,38}-with-tomli
     coverage-all
     docs-test-{html,linkcheck,coverage,doctest,spelling}
 
 labels =
-    test = py{312,311,310,39,38},py{312,311,310,39,38}-with-yaml,py{312,311,310,39,38}-with-sphinx{4,5,6,7},py{312,311,310,39,38}-with-tomli,coverage-all
-    py3.8 = py38,py38-with-yaml,py38-with-sphinx{4,5,6,7},py38-with-tomli,coverage-all
-    py3.9 = py39,py39-with-yaml,py39-with-sphinx{4,5,6,7},py39-with-tomli,coverage-all
-    py3.10 = py310,py310-with-yaml,py310-with-sphinx{4,5,6,7},py310-with-tomli,package,coverage-all
-    py3.11 = py311,py311-with-yaml,py311-with-sphinx{4,5,6,7},py311-with-tomli,package,coverage-all
-    py3.12 = py312,py312-with-yaml,py312-with-sphinx{4,5,6,7},py312-with-tomli,package,coverage-all
+    test = py{312,311,310,39,38},py{312,311,310,39,38}-with-yaml,py{312,311,310,39,38}-with-sphinx{5,6,7},py{312,311,310,39,38}-with-tomli,coverage-all
+    py3.8 = py38,py38-with-yaml,py38-with-sphinx{5,6,7},py38-with-tomli,coverage-all
+    py3.9 = py39,py39-with-yaml,py39-with-sphinx{5,6,7},py39-with-tomli,coverage-all
+    py3.10 = py310,py310-with-yaml,py310-with-sphinx{5,6,7},py310-with-tomli,package,coverage-all
+    py3.11 = py311,py311-with-yaml,py311-with-sphinx{5,6,7},py311-with-tomli,package,coverage-all
+    py3.12 = py312,py312-with-yaml,py312-with-sphinx{5,6,7},py312-with-tomli,package,coverage-all
     docs = docs-test-{html,linkcheck,coverage,doctest,spelling}
 
 
@@ -149,7 +149,7 @@ commands =
         {posargs:tests}
 
 
-[testenv:py{312,311,310,39,38}-with-sphinx{4,5,6,7}]
+[testenv:py{312,311,310,39,38}-with-sphinx{5,6,7}]
 description = run tests with {basepython} and sphinx
 pass_env =
     {[testenv]pass_env}
@@ -161,7 +161,6 @@ extras =
     testing
     yaml
 deps =
-    sphinx4: sphinx>=4,<5
     sphinx5: sphinx>=5,<6
     sphinx6: sphinx>=6,<7
     sphinx7: sphinx>=7,<8