dont include rest_framework in tests if it is not present

Author: bckohan

django_enum/tests/settings.py

@@ -44,7 +44,6 @@
 INSTALLED_APPS = [
     'django_enum.tests.djenum',
     'django_enum.tests.tmpls',
-    'rest_framework',
     'django.contrib.auth',
     'django.contrib.contenttypes',
     'django.contrib.sessions',
@@ -54,6 +53,12 @@
     'django.contrib.admin',
 ]
 
+try:
+    import rest_framework
+    INSTALLED_APPS.insert(0, 'rest_framework')
+except (ImportError, ModuleNotFoundError):
+    pass
+
 try:
     import enum_properties
     INSTALLED_APPS.insert(0, 'django_enum.tests.enum_prop')