Avoid py38 test failure on Windows

[Tronic]

Reduces test data size to 3 MB instead of 30 MB. This should not affect what the tests are trying to accomplish but makes them run faster, which apparently was an issue on Windows until now. Each test includes a large number of requests each of which include this data, and I could get all of them passing if I commented out some of the others, without reducing data size.

Reducing data size makes the tests run much faster and now they pass on my Windows virtual machine with all requests enabled.

[codecov]

Codecov Report

Merging #1816 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1816   +/-   ##
=======================================
  Coverage   91.94%   91.94%           
=======================================
  Files          23       23           
  Lines        2309     2309           
  Branches      428      428           
=======================================
  Hits         2123     2123           
  Misses        143      143           
  Partials       43       43

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[Tronic]

This is merged to #1808 and maintaining two branches is too troublesome. Closing this in favour of the other one.