fix(django): Add sync_capable to SentryWrappingMiddleware

[szokeasaurusrex]

Apparently, not having the sync_capable on the SentryWrappingMiddleware sometimes breaks things when we have an async-only middleware, such as ServeStatic.

Fixes #3506

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.26%. Comparing base (53897ff) to head (2c6e450).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3510      +/-   ##
==========================================
- Coverage   84.26%   84.26%   -0.01%     
==========================================
  Files         136      136              
  Lines       13894    13895       +1     
  Branches     2938     2938              
==========================================
  Hits        11708    11708              
  Misses       1458     1458              
- Partials      728      729       +1     

Files with missing lines	Coverage Δ
sentry_sdk/integrations/django/middleware.py	91.11% <100.00%> (+0.09%)	⬆️

... and 1 file with indirect coverage changes

[szokeasaurusrex]

@sentrivana or @antonpirker, do you think we need a test for this? I am not sure how exactly we would test this change

[sentrivana]

Nice!

do you think we need a test for this? I am not sure how exactly we would test this change

Do we already have any middleware tests? It'd be great to have a test case that sets up a middleware, then inits the SDK, and then checks whether the wrapped middleware has all the expected attributes, including sync_capable.

If there's already a similar test case, we can just add this to it/repurpose that. If we don't have this, that's a blind spot we should fix. But if it's too much effort, you can just create a ticket and eventually we'll get to it during maintenance.

[szokeasaurusrex]

@sentrivana @antonpirker, I added a test. Would appreciate if one of you could check that it looks reasonable