remove all obsolete "CurrentVersionCode: 0" entries

Setting CVC to 0 was an old way to make `fdroid update` use the highest
versionCode as the CurrentVersionCode.  This has been obsolete for a while,
so its time to purge these.  Now, when CurrentVersionCode is unset, then
the highest versionCode is used.

sed -i  -e '/^CurrentVersionCode: 0$/d' -e "/^CurrentVersion: '0'$/d" *.yml
1 job for master in 3 minutes and 40 seconds (queued for 1 second)
Status Name Job ID Coverage
passed lint #459452697