We've only been updating translatable strings for Weblate rarely based on
MAINTAINING.md#translations-from-weblate. Since Weblate pulls in commits live
from qTox, we should generate the translatable strings as soon as they're
introduced so that translators can not waste time translating deleted strings,
and can spend time translating new strings.
We can't auto-commit the changes in CI due to our requirement of signed
commits, so just fail CI if any new strings are found.
Move it into its own job, it doesn't depend on docker or the build, and doesn't need to run for debug/release/full/minimal