Fixes the css file path included in the debian package.

debian/jitsi-meet.install

 *.json					/usr/share/jitsi-meet/
 *.html					/usr/share/jitsi-meet/
 *.ico					/usr/share/jitsi-meet/
-*.css					/usr/share/jitsi-meet/
 libs					/usr/share/jitsi-meet/
 service					/usr/share/jitsi-meet/
+css/all.css 			/usr/share/jitsi-meet/css/
 sounds					/usr/share/jitsi-meet/
 fonts					/usr/share/jitsi-meet/
 images					/usr/share/jitsi-meet/