[FR] Improved fix for broken test test-use_readme.R

[ilyaZar]

Via 9ad9775 a test fix for test-use_readme() is done that skips the test in non-interactive mode.

However, when eliminating the devtools:::build_readme() call at the very end, the test passes successfully in non-interactive mode, so no need for skipping.

Hence, to improve codecov one may delete the devtools:::build_readme() line and run the test as usual.

Can be fixed via #1122