in_target_language can return ratios above 1.0 (again)

[osma]

Bug #112 seems to have resurfaced. Again, in_target_language('It was a true gift', lang=('en','de')) returns 1.6666... in simplemma 1.1.1.

Looking at the code for proportion_in_target_languages, it was changed back to the buggy algorithm that uses sum() in #116 (by @juanjoDiaz) and the unit test guarding against this bug was simply removed in the same PR :(

[adbar]

@osma Thank you for reporting the issue, this one slipped through.