Corrected pathlib.Path detection when saving

[radarhere]

Resolves #5632

As #3825 did for open(), this fixes detecting pathlib.Path in save().

Pillow/src/PIL/Image.py

Lines 2183 to 2188 in 68c5f2d

	if isPath(fp):
	filename = fp
	open_fp = True
	elif isinstance(fp, Path):
	filename = str(fp)
	open_fp = True

The above code will never execute the second block, because isPath returns true for Path instances.

Pillow/src/PIL/_util.py

Lines 5 to 6 in 68c5f2d

	def isPath(f):
	return isinstance(f, (bytes, str, Path))

So this PR swaps the order.