Remove use of the deprecated binary parameter of the Python item exporter

[Gallaecio]

Needed for the next Scrapy version due to scrapy/scrapy#6007.

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (a55cc06) 95.53% compared to head (1457278) 95.54%.

❗ Current head 1457278 differs from pull request most recent head c75f5e4. Consider uploading reports for the commit c75f5e4 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #71   +/-   ##
=======================================
  Coverage   95.53%   95.54%           
=======================================
  Files          14       14           
  Lines         739      740    +1     
=======================================
+ Hits          706      707    +1     
  Misses         33       33           

Files Changed	Coverage Δ
sh_scrapy/crawl.py	87.14% <100.00%> (+0.28%)	⬆️
sh_scrapy/extension.py	100.00% <100.00%> (ø)

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