Update CI configuration

Author: ellmetha

.github/workflows/ci.yml

@@ -48,13 +48,6 @@ jobs:
           'postgres',
           'sqlite',
         ]
-        exclude:
-          - python-version: 3.5
-            django-version: "django>=3.0,<3.1"
-          - python-version: 3.5
-            django-version: "django>=3.1,<3.2"
-          - python-version: 3.5
-            django-version: "django>=3.2,<4.0"
 
     steps:
     - uses: actions/checkout@v2