Update testing_tools.dart

[takassh]

Hi, thank you for publishing this package! It is so useful for us!

I found a subtle need.
pumpDeviceBuilder does not have textScaleSize argument, so I added it!

[codecov-commenter]

Codecov Report

Merging #153 (c687e26) into master (b8cf574) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #153   +/-   ##
=======================================
  Coverage   99.72%   99.72%           
=======================================
  Files          12       12           
  Lines         364      364           
=======================================
  Hits          363      363           
  Misses          1        1           

Impacted Files	Coverage Δ
packages/golden_toolkit/lib/src/testing_tools.dart	100.00% <ø> (ø)

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[coreysprague]

@takassh thanks for the contribution! Would you mind adding a test to demonstrate the behavior?

[takassh]

@coreysprague
np!
I added a test
it means you can easily compare text scale among other devices

[coreysprague]

thanks! I'll get this out in a new release shortly

[takassh]

@coreysprague
thank you!