I would strongly encourage getting rid of the dev branch. It is redundant in almost all cases.

Instead think of the master branch as the integration branch. This is where everything gets merged ready for a new release. But the master branch itself is not a release. You can automatically deploy the master branch to a staging or "next" environment if you wish.

For releases, use tags. That's what they are for. If necessary you can make one or more "maint" branches where you backport important fixes from the master branch on to release branches to create patch level release versions.