Translated using Weblate (#5611)

Co-authored-by: Frank JIn <chinafrank0129@outlook.com>
Co-authored-by: Kevin Papst <kevin@kevinpapst.de>
Co-authored-by: Kolappan N <kolappan@users.noreply.hosted.weblate.org>
Co-authored-by: Marc Sánchez Díaz <msanchez@aporta.biz>
Co-authored-by: Martin Maslyankov <m.maslyankov@me.com>
Co-authored-by: Wolf <wolski.marex@gmail.com>
Co-authored-by: asefeee <3470154407@qq.com>
Co-authored-by: lolly76 <thelolly76@gmail.com>

translations/messages.bg.xlf

@@ -280,7 +280,7 @@
       </trans-unit>
       <trans-unit id="FveKfWM" resname="username" xml:space="preserve">
         <source>username</source>
-        <target state="translated">Потребителско име</target>
+        <target state="translated">Потребител</target>
       </trans-unit>
       <trans-unit id="yQRveje" resname="description" approved="no" xml:space="preserve">
         <source>Description</source>