[LyX/2.3.x] Update bg.po from Veselin

[Pavel Sanda]

commit b10777e0599f01eb06d14cae7a0da88ec9aab70b
Author: Pavel Sanda <sanda at lyx.org>
Date:   Wed Mar 31 14:36:23 2021 +0200

    Update bg.po from Veselin

 po/bg.po | 4147 +++++++++++++++++++++++++-------------------------------------
 1 files changed, 1637 insertions(+), 2510 deletions(-)