fix(scrapy): Drop deprecated spider arg from Scrapy proxy middleware methods

[vdusek]

Scrapy ≥2.14 deprecated the spider parameter on downloader-middleware methods and emits a ScrapyDeprecationWarning on every run for any method that still requires it. ApifyHttpProxyMiddleware.process_request and process_exception only used spider for debug logging, so this drops the parameter (and its docstring/log references), mirroring the already-migrated ActorDatasetPushPipeline.

A regression test registers the middleware via DownloaderMiddlewareManager and asserts no "requires a spider argument" warning is emitted.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.87%. Comparing base (0daca28) to head (0e941bb).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #977      +/-   ##
==========================================
- Coverage   89.90%   89.87%   -0.04%     
==========================================
  Files          49       49              
  Lines        3091     3091              
==========================================
- Hits         2779     2778       -1     
- Misses        312      313       +1     

Flag	Coverage Δ
e2e	35.91% <0.00%> (ø)
integration	56.90% <0.00%> (+0.03%)	⬆️
unit	78.68% <100.00%> (-0.07%)	⬇️

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