Bump version to 4.5-beta

The feature freeze for 4.5 is now active.

From here on we'll focus only on fixing bugs to stabilize the development
branch and release 4.5-stable within a few weeks.

version.py

@@ -3,7 +3,7 @@ name = "Godot Engine"
 major = 4
 minor = 5
 patch = 0
-status = "dev"
+status = "beta"
 module_config = ""
 website = "https://godotengine.org"
 docs = "latest"