Test psycopg with Python 3.13

This was made possible with release 3.2.2 - see https://github.com/psycopg/psycopg/blob/3.2.3/docs/news.rst#psycopg-322

Author: ddabble

tox.ini

@@ -1,11 +1,8 @@
 [tox]
 envlist =
-    py{38,39,310,311,312}-dj42-{sqlite3,postgres,mysql,mariadb},
-    py{310,311,312}-dj50-{sqlite3,postgres,mysql,mariadb},
-    py{310,311,312}-djmain-{sqlite3,postgres,mysql,mariadb},
-    # DEV: Add `313` to the Python versions above (so that postgres is tested with 3.13)
-    #      when `psycopg` provides binaries for 3.13
-    py313-dj{42,50,main}-{sqlite3,mysql,mariadb},
+    py{38,39,310,311,312,313}-dj42-{sqlite3,postgres,mysql,mariadb},
+    py{310,311,312,313}-dj50-{sqlite3,postgres,mysql,mariadb},
+    py{310,311,312,313}-djmain-{sqlite3,postgres,mysql,mariadb},
     docs,
     lint