Added filename placeholder in winbuild URL

[radarhere]

There are several places in winbuild/build_prepare.py where the "filename" is replicated in the "url"

Pillow/winbuild/build_prepare.py

Lines 163 to 165 in 822ec3d

	"zlib": {
	"url": f"https://zlib.net/zlib{V['ZLIB_DOTLESS']}.zip",
	"filename": f"zlib{V['ZLIB_DOTLESS']}.zip",

I wonder if

"zlib": {
    "url": "https://zlib.net/FILENAME",
    "filename": f"zlib{V['ZLIB_DOTLESS']}.zip",

is neater, reducing duplication?

Feel free to reject if others think it isn't simpler.

[nulano]

This string probably fits on a single line now.

[radarhere]

You're right. I've pushed a commit.