Changing from version: master to version: git will prevent the snap being built with the text 'master' as the version, but instead use the latest git tag or version info. This makes it easier to figure out which build is which in the store.
As a text editor, micro will need to be able to edit files outside the confined world snap gives it. So this PR changes the confinement model of micro from strict to classic, making it way more useful on snap enabled systems.