Fix RemovedInDjango41Warning deprecation warnings

Author: zerolab

setup.py

@@ -2,17 +2,20 @@
 
 from setuptools import find_packages, setup
 
-from src.wagtail_headless_preview import __version__
-
 
 this_directory = path.abspath(path.dirname(__file__))
 with open(path.join(this_directory, "README.md"), encoding="utf-8") as f:
     long_description = f.read()
 
+version = {}
+with open(
+    path.join(this_directory, "src", "wagtail_headless_preview", "version.py")
+) as f:
+    exec(f.read(), version)
 
 setup(
     name="wagtail-headless-preview",
-    version=__version__,
+    version=version["__version__"],
     description="Enhance Wagtail previews in headless setups.",
     long_description=long_description,
     long_description_content_type="text/markdown",

src/wagtail_headless_preview/__init__.py

@@ -1,7 +1,13 @@
-default_app_config = "wagtail_headless_preview.apps.WagtailHeadlessPreviewConfig"
+from django import VERSION as DJANGO_VERSION
 
-VERSION = (0, 1, 4)
-__version__ = ".".join(map(str, VERSION))
+from .version import VERSION, __version__  # noqa
+
+
+if DJANGO_VERSION >= (3, 2):
+    # The declaration is only needed for older Django versions
+    pass
+else:
+    default_app_config = "wagtail_headless_preview.apps.WagtailHeadlessPreviewConfig"
 
 
 def setup():

src/wagtail_headless_preview/version.py

@@ -0,0 +1,2 @@
+VERSION = (0, 1, 4)
+__version__ = ".".join(map(str, VERSION))

tests/testapp/__init__.py

@@ -1 +1,8 @@
-default_app_config = "tests.testapp.apps.WagtailHeadlessPreviewTestsAppConfig"
+from django import VERSION as DJANGO_VERSION
+
+
+if DJANGO_VERSION >= (3, 2):
+    # The declaration is only needed for older Django versions
+    pass
+else:
+    default_app_config = "tests.testapp.apps.WagtailHeadlessPreviewTestsAppConfig"