Updated mean income in ogzaf_default_parameters.json

[rickecon]

This PR updates the mean_income_data value to 123809.11 in ogzaf_default_parameters.json. This value is in South African Rand and is equal to GDP per capita in 2022.

cc: @jdebacker

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.46%. Comparing base (8060f56) to head (55a7827).
Report is 13 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #62   +/-   ##
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  Coverage   56.46%   56.46%           
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  Files          12       12           
  Lines         356      356           
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  Hits          201      201           
  Misses        155      155           

Flag	Coverage Δ
unittests	56.46% <ø> (ø)

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