Incompatible version convention with composer

[bilogic]

Generally, in composer,

if the git branch starts with a non-numeric, dev should be prepended as dev-, e.g. dev-main, dev-master
if the git branch starts with a number, dev should be appended as -dev, e.g. 10.x-dev

acappella always prepends (dev-master, dev-10.x).

Usingdev-10.x makes it incompatible with composer, see composer/composer#11770