Do not run djstripe checks on builders

We found this while performing the deploy.
Builders do not have access to the database, and `djstripe` runs some checks
that access the database to know if there are API keys defined there.

Author: humitos

readthedocs/projects/apps.py

@@ -1,6 +1,10 @@
 """Project app config."""
 
+import socket
+
 from django.apps import AppConfig
+from django.conf import settings
+from django.core.checks.registry import registry
 
 
 class ProjectsConfig(AppConfig):
@@ -13,3 +17,13 @@ def ready(self):
         import readthedocs.projects.tasks.builds  # noqa
         import readthedocs.projects.tasks.search  # noqa
         import readthedocs.projects.tasks.utils  # noqa
+
+        # HACK: remove djstripe initial checks.
+        # It performs checks that require access to the database, which make the builders to fail.
+        # Note this code has to be executed _after_ djstripe has been initialized.
+        #
+        # https://github.com/dj-stripe/dj-stripe/blob/8e536409b815b2a393ef1ba8eac3d27bd69a5664/djstripe/checks.py#L20
+        if settings.DEBUG or socket.gethostname().startswith("build-"):
+            registry.registered_checks = {
+                item for item in registry.registered_checks if "djstripe" not in item.tags
+            }