Drop testing for Wagtail 6.0

- update the README to reflect the supported versions.

README.md

@@ -20,7 +20,7 @@ This package is in maintenance mode and will not receive new features. Consider
 
 - Python 3.8, 3.9, 3.10, 3.11, 3.12
 - Django 4.2, 5.0
-- Wagtail 5.2, 6.0, 6.1, 6.2
+- Wagtail 5.2, 6.1, 6.2
 
 ## Installation
 

tox.ini

@@ -3,15 +3,15 @@ skipsdist = True
 usedevelop = True
 
 envlist =
-    python{3.8,3.9,3.10,3.11}-django{4.2,5.0,main}-wagtail{5.2,6.0,6.1,6.2,main}
-    python{3.10,3.11,3.12}-django{5.0,main}-wagtail{5.2,6.0,6.1,6.2,main}
+    python{3.8,3.9,3.10,3.11}-django{4.2,5.0,main}-wagtail{5.2,6.1,6.2,main}
+    python{3.10,3.11,3.12}-django{5.0,main}-wagtail{5.2,6.1,6.2,main}
 
 [gh]
 python =
     3.8 = python3.8-django{4.2}-wagtail{5.2}
     3.9 = python3.9-django{4.2}-wagtail{5.2,main}
-    3.10 = python3.10-django{4.2,5.0}-wagtail{5.2,6.0,6.1,6.2,main}
-    3.11 = python3.11-django{4.2,5.0}-wagtail{6.0,6.1,6.2,main}
+    3.10 = python3.10-django{4.2,5.0}-wagtail{5.2,6.1,6.2,main}
+    3.11 = python3.11-django{4.2,5.0}-wagtail{6.1,6.2,main}
     3.12 = python3.12-djangomain-wagtailmain
 
 [testenv]
@@ -33,7 +33,6 @@ deps =
     djangomain: git+https://github.com/django/django.git@main#egg=Django
 
     wagtail5.2: wagtail>=5.2,<6.0
-    wagtail6.0: wagtail>=6.0,<6.1
     wagtail6.1: wagtail>=6.1,<6.2
     wagtail6.2: wagtail>=6.2,<6.3
     wagtailmain: git+https://github.com/wagtail/wagtail.git#egg=wagtail