Evaluating the dependency graph potentially executes Python code when
evaluating drivers. In specific situations (see T91046) this could
deadlock Blender entirely. Temporarily releasing the GIL when evaluating
the depsgraph resolves this.
This is an improved version of
rBfc460351170478e712740ae1917a2e24803eba3b, thanks @brecht for the diff!
Manifest task: T91046