We do not have this optional test dependency packaged yet.

--- singledispatch-json-0.5.0/tox.ini.orig
+++ singledispatch-json-0.5.0/tox.ini
@@ -178,7 +178,6 @@
     /bin/bash -c "DISPLAY=:0 firefox 'htmlcov/index.html'"
 
 [coverage:run]
-plugins = coverage_pyver_pragma
 
 [coverage:report]
 fail_under = 100
--- singledispatch-json-0.5.0/tests/requirements.txt.orig
+++ singledispatch-json-0.5.0/tests/requirements.txt
@@ -1,6 +1,5 @@
 coincidence>=0.2.0
 coverage>=5.1
-coverage-pyver-pragma>=0.2.1
 importlib-metadata>=3.6.0
 iniconfig!=1.1.0,>=1.0.1
 pytest>=6.0.0