Changed IPTC tile tuple to match other plugins

[radarhere]

Looking at

Pillow/src/PIL/IptcImagePlugin.py

Lines 131 to 133 in 0988703

	self.tile = [
	("iptc", (compression, offset), (0, 0, self.size[0], self.size[1]))
	]

I find this odd, as it does not match the structure that we otherwise have for self.tile.

Pillow/src/PIL/ImageFile.py

Lines 93 to 97 in 0988703

	class _Tile(NamedTuple):
	encoder_name: str
	extents: tuple[int, int, int, int]
	offset: int
	args: tuple | str | None

Pillow/src/PIL/JpegImagePlugin.py

Line 396 in 0988703

self.tile = [("jpeg", (0, 0) + self.size, 0, (rawmode, ""))]

The reason this problem has not been found by the test suite is that no test actually opens a valid IPTC image.

This PR changes the self.tile tuple to match the format used in other plugins.

self.tile = [("iptc", (0, 0) + self.size, offset, compression)]

I've reversed-engineered test data for _open from the code.