Allow package builds from release tarballs to provide the version because Go
records the main module version as "(devel)" outside the module proxy. This
keeps Headscale's database upgrade checks enabled for packaged releases.

Signed-off-by: coolsnowwolf <coolsnowwolf@gmail.com>
---
--- a/hscontrol/types/version.go
+++ b/hscontrol/types/version.go
@@ -24,0 +25,2 @@
+var version = "dev"
+
@@ -45 +47 @@
-		Version:   "dev",
+		Version:   version,