Fix false positive test runs

[wiruzx]

Because we have pipe to xcpretty at the end of the test.sh script, returned exit code is zero even if xcodebuild fails.
We need to enable pipefail option in order to fix that behaviour.
For more information see documentation on set.

[codecov-commenter]

Codecov Report

Merging #680 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #680   +/-   ##
=======================================
  Coverage   44.77%   44.77%           
=======================================
  Files          98       98           
  Lines        5119     5119           
=======================================
  Hits         2292     2292           
  Misses       2827     2827           

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