[BUG] - Small memory leak in source handling

[FiniteSingularity]

Describe the bug
If user selects no source, but there was an existing source before, the weak source is not released.

Expected behavior
We should not leak memory!

Additional context
In update function, wherever a weak source is checked, make sure to add pointer check and release if pointer already exists. e.g.:

	if (color_source) {
		obs_weak_source_release(filter->color_source);
		filter->color_source =
			obs_source_get_weak_source(color_source);
		obs_source_release(color_source);
	} else {
		if (filter->color_source) {
			obs_weak_source_release(filter->color_source);
		}
		filter->color_source = NULL;
	}