Include inner error message in Display for SerdeError

[XAMPPRocky]

Motivation

Currently the error message for deserialisation error is opaque not saying why it failed. This is particularly annoying when you're watching CRDs as if you're testing a new version, and there is something in a new CRD that is breaking your current service, you don't see what caused that breakage

Solution

Just include the inner error message in the display impl.

[clux]

LGTM. Note that for these cases you can in general get this information out of an error formatter that walks the chain like miette.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.6%. Comparing base (72eef44) to head (1990d6c).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #1481   +/-   ##
=====================================
  Coverage   74.6%   74.6%           
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  Files         79      79           
  Lines       6871    6871           
=====================================
  Hits        5125    5125           
  Misses      1746    1746