Remove pypy from Django 3.2 testing

There are a few test failures with pypy and Django 3.2. Since 3.2 is out
of long-term support, drop these from the test matrix.

tox.ini

@@ -4,12 +4,12 @@ envlist =
     {3.10,3.11,3.12,pypy310}-main
     {3.10,3.11,3.12,pypy310}-5.0.x
     {3.8,3.9,3.10,3.11,3.12,pypy38,pypy39,pypy310}-4.2.x
-    {3.8,3.9,3.10,pypy38,pypy39,pypy310}-3.2.x
+    {3.8,3.9,3.10}-3.2.x
 
 
-# Don't run coverage when testing with pypy:
+# Don't run coverage if it triggers ValueError("site must subclass AdminSite")
 # see https://github.com/nedbat/coveragepy/issues/1382
-[testenv:pypy310-main,pypy310-5.0.x,{pypy38,pypy39,pypy310}-4.2.x,{pypy38,pypy39,pypy310}-3.2.x]
+[testenv:pypy310-5.0.x,{pypy38,pypy39,pypy310}-4.2.x]
 commands =
     pip install --upgrade pip
     pip install -e .[tests]