Increase the send timeout for mains devices to 3s

[puddly]

Zigpy will internally retry regardless but this will prevent unnecessary retries (or those that interfere with route discovery).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.21%. Comparing base (1f61e0b) to head (d5235a3).
Report is 1 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #673   +/-   ##
=======================================
  Coverage   99.21%   99.21%           
=======================================
  Files          51       51           
  Lines        3691     3691           
=======================================
  Hits         3662     3662           
  Misses         29       29           

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