Upload staticfiles to S3 (#12220)

Django 4.2 deprecated the way that storages are handled and introduced
`STORAGES` setting. Then Django 5.2 removed the old pattern and our
staticfiles were broken after the upgrade.

This commit makes a very simple usage of `STORAGES` to define the
`staticfiles` storage so these files go to S3.

Note that I'm not changing the underlying configuration of the other
storages we use (build media, build tools, etc) for now; but we could
upgrade our code to follow the new pattern if we want to.

I tested this from `web-extra` and now the message is different:

```
docs@web-extra-i-0ef973eb0da33af39(org):~/checkouts/readthedocs.org$ django-admin collectstatic

You have requested to collect static files at the destination
location as specified in your settings.

This will overwrite existing files!
Are you sure you want to do this?

Type 'yes' to continue, or 'no' to cancel: yes

329 static files copied.
docs@web-extra-i-0ef973eb0da33af39(org):~/checkouts/readthedocs.org$
```

Besides, I can see the ext-theme files in the static S3 bucket now.

Closes #12211

Author: humitos

readthedocs/settings/base.py

@@ -1030,6 +1030,15 @@ def GITHUB_APP_CLIENT_ID(self):
     # Used by readthedocs.aws.security_token_service.
     AWS_STS_ASSUME_ROLE_ARN = "arn:aws:iam::1234:role/SomeRole"
 
+    @property
+    def STORAGES(self):
+        # https://django-storages.readthedocs.io/en/latest/backends/amazon-S3.html
+        return {
+            "staticfiles": {
+                "BACKEND": self.RTD_STATICFILES_STORAGE,
+            },
+        }
+
     @property
     def USING_AWS(self):
         """Return True if we are using AWS as our storage/cloud provider."""

requirements/deploy.txt

@@ -166,7 +166,7 @@ django-safemigrate==5.3
     # via -r requirements/pip.txt
 django-simple-history==3.8.0
     # via -r requirements/pip.txt
-django-storages[boto3]==1.14.6
+django-storages[s3]==1.14.6
     # via -r requirements/pip.txt
 django-structlog==2.2.0
     # via -r requirements/pip.txt

requirements/docker.txt

@@ -174,7 +174,7 @@ django-safemigrate==5.3
     # via -r requirements/pip.txt
 django-simple-history==3.8.0
     # via -r requirements/pip.txt
-django-storages[boto3]==1.14.6
+django-storages[s3]==1.14.6
     # via -r requirements/pip.txt
 django-structlog==2.2.0
     # via -r requirements/pip.txt

requirements/pip.in

@@ -116,7 +116,7 @@ django-cors-headers
 # User agent parsing - used for analytics purposes
 user-agents
 
-django-storages[boto3]
+django-storages[s3]
 
 
 # Required only in development and linting

requirements/pip.txt

@@ -129,7 +129,7 @@ django-safemigrate==5.3
     # via -r requirements/pip.in
 django-simple-history==3.8.0
     # via -r requirements/pip.in
-django-storages[boto3]==1.14.6
+django-storages[s3]==1.14.6
     # via -r requirements/pip.in
 django-structlog==2.2.0
     # via -r requirements/pip.in

requirements/testing.txt

@@ -173,7 +173,7 @@ django-safemigrate==5.3
     # via -r requirements/pip.txt
 django-simple-history==3.8.0
     # via -r requirements/pip.txt
-django-storages[boto3]==1.14.6
+django-storages[s3]==1.14.6
     # via -r requirements/pip.txt
 django-structlog==2.2.0
     # via -r requirements/pip.txt