Removed pytest version pin from Tox.

tox.ini

@@ -7,7 +7,7 @@ skip_missing_interpreters = true
 
 [testenv]
 deps =
-	test: pytest<6.0
+	test: pytest
 	test,cov: {[testenv:cov]deps}
 	test,py{36,37,38,39,310}-{type,mypy}: colorama
 	py{36,37,38,39,310}-{type,mypy}: {[testenv:mypy]deps}