Improve paho-mqtt and mosqitto fixtures

[amotl]

What's Inside

• paho-mqtt: Ignore deprecation warnings about Callback API v1
• mosquitto: Don't always pull OCI image

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.83%. Comparing base (900aa2f) to head (d04576c).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #26      +/-   ##
==========================================
+ Coverage   95.73%   95.83%   +0.10%     
==========================================
  Files           5        5              
  Lines         164      168       +4     
==========================================
+ Hits          157      161       +4     
  Misses          7        7              

Flag	Coverage Δ
unittests	95.83% <100.00%> (+0.10%)	⬆️

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