Update translations (Weblate)

Co-authored-by: Hosted Weblate <hosted@weblate.org>
Co-authored-by: Languages add-on <noreply-addon-languages@weblate.org>
Co-authored-by: Matthaiks <kitynska@gmail.com>
Co-authored-by: Sveinn í Felli <sv1@fellsnet.is>
Co-authored-by: Wim Benes <fryskefirefox@gmail.com>
Translate-URL: https://hosted.weblate.org/projects/tb-android/app-store-metadata-k9mail/is/
Translate-URL: https://hosted.weblate.org/projects/tb-android/app-store-metadata-k9mail/pl/
Translate-URL: https://hosted.weblate.org/projects/tb-android/widget-unread/fy/
Translate-URL: https://hosted.weblate.org/projects/tb-android/widget-unread/nl/
Translation: K-9 Mail/Thunderbird/App Store Metadata (K-9 Mail)
Translation: K-9 Mail/Thunderbird/widget-unread