Change VERSION back to v4.5.x on main

Specific version numbers should be fixed in the tag, not on the branch.

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

Variables.mk

@@ -13,7 +13,7 @@ VARLIST := OS
 # Project Information
 VARLIST += WAREWULF VERSION RELEASE
 WAREWULF ?= warewulf
-VERSION ?= 4.5.0rc1
+VERSION ?= 4.5.x
 RELEASE_INCREMENT ?= 1
 
 GIT_HASH := $(shell test -e .git && git log -1 --format="%h")