fix: don't pass quotes to espeak (#3286)

Previously, the text was wrapped in an additional set of quotes that was passed
to Espeak. This could result in different phonemization in certain edges and
caused the insertion of an initial separator "_" that had to be removed.
Compare:
$ espeak-ng -q -b 1 -v en-us --ipa=1 '"A"'
_ˈɐ
$ espeak-ng -q -b 1 -v en-us --ipa=1 'A'
ˈeɪ

Fixes #2619