Avoid global Logger as this conflicts with a native class in Godot 4.5

[dreed-sd]

Fixes #709

ERROR: res://addons/gut/utils.gd:95 - Parse Error: The member "Logger" shadows a native class.

[dreed-sd]

The Logger commit fyi: godotengine/godot#91006

[murilosr]

Worked great here! Thanks

[bitwes]

Thanks! I was a little hesitant to merge it since it seem sodd they would take the name Logger from everyone. The more I thought about it though, it would be good to not use that name in Gut regardless of whether Godot keeps using it.