fix(integrations/dramatiq): use set_transaction_name

[timdrijvers]

The Dramatiq integration is using a deprecated method to set the scope's transaction name, use set_transaction_name instead.

"Assigning to scope.transaction directly is deprecated: use scope.set_transaction_name() instead."

[sentrivana]

Thank you @timdrijvers!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.58%. Comparing base (08bbe00) to head (c35e622).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4175      +/-   ##
==========================================
+ Coverage   79.57%   79.58%   +0.01%     
==========================================
  Files         141      141              
  Lines       15737    15737              
  Branches     2675     2675              
==========================================
+ Hits        12522    12525       +3     
+ Misses       2369     2367       -2     
+ Partials      846      845       -1     

Files with missing lines	Coverage Δ
sentry_sdk/integrations/dramatiq.py	80.72% <100.00%> (ø)

... and 3 files with indirect coverage changes