[Weblate] update_tm.sh fails

Originally created by @hefee on #17673 (Redmine)

it fails:

/var/lib/weblate/scripts/update_tm.sh: 10: /var/lib/weblate/scripts/update_tm.sh: build_tmdb: not found

running it as weblate user it runs successfully.

I expect that the $PATH for cron does not contain /usr/local/bin/:

$ whereis build_tmdb
build_tmdb: /usr/local/bin/build_tmdb

I’d suggest to use the absolute path in update_tm.sh, than we are independent of cron’s PATH settings.