Drop the zigpy Requests class

[puddly]

This API was removed in the latest release of zigpy.

[codecov]

Codecov Report

❌ Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 98.79%. Comparing base (37241f1) to head (1ca174a).
⚠️ Report is 1 commits behind head on dev.

Files with missing lines	Patch %	Lines
zigpy_deconz/zigbee/application.py	92.85%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #267   +/-   ##
=======================================
  Coverage   98.79%   98.79%           
=======================================
  Files           7        7           
  Lines         911      914    +3     
=======================================
+ Hits          900      903    +3     
  Misses         11       11           

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