utils,playertoolbar: Use regular colon as time divider

The GNOME HIG suggests using an alternate character for the hour,
minutes divider (Teams/Design/hig-www#127). This leads to reversed time
ordering in RTL languages.

Use „:” (U+003A) again instead of „∶” (U+2236) for now. This will fix
the reversed time in RTL languages.

Fixes: #509
3 jobs for wip/mschraal/playertoolbar-rtl-colon-fix-41-backport in 8 minutes and 14 seconds (queued for 1 second)