test against django 6.0 alpha 1

Author: bckohan

.github/workflows/test.yml

@@ -41,6 +41,7 @@ jobs:
           - '4.2' # LTS April 2026
           - '5.1' # December 2025
           - '5.2' # LTS April 2028
+          - '6.0a1' # alpha prerelease
         exclude:
           - django-version: '4.2'
             postgres-version: '9.6'
@@ -91,6 +92,17 @@ jobs:
           # https://github.com/psycopg/psycopg2/pull/1695
           - python-version: '3.14'
             psycopg-version: 'psycopg2'
+          
+          - python-version: '3.9'
+            django-version: '6.0a1'
+          - python-version: '3.10'
+            django-version: '6.0a1'
+          - python-version: '3.11'
+            django-version: '6.0a1'
+          - python-version: '3.12'
+            django-version: '6.0a1'
+          - python-version: '3.13'
+            django-version: '6.0a1'
 
     env:
       RDBMS: postgres