Add Django 3.2 to GitHub Actions test matrix

Author: Tenzer

.github/workflows/tests.yml

@@ -10,7 +10,7 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ["3.6", "3.7", "3.8", "3.9"]
-        django: ["2.2", "3.0", "3.1"]
+        django: ["2.2", "3.0", "3.1", "3.2"]
         django-rest-framework: ["3.12", "master"]
     env:
       PYTHON: ${{ matrix.python-version }}