Update reference values for WB-datareader tests

[danielhuppmann]

Description of PR

The values in the WorldBank data catalogue changed, so this PR updates the expected values in the integration tests.

[codecov[bot]]

Codecov Report

Merging #724 (28c2e12) into main (d75d4ce) will not change coverage. The diff coverage is n/a.

@@          Coverage Diff          @@
##            main    #724   +/-   ##
=====================================
  Coverage   95.0%   95.0%           
=====================================
  Files         59      59           
  Lines       6003    6003           
=====================================
  Hits        5707    5707           
  Misses       296     296           

Impacted Files	Coverage Δ
tests/test_datareader.py	82.6% <ø> (ø)

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