archive-zip: widen zlib_deflate_raw()'s maxsize local to size_t

Prep for the upcoming git_deflate_bound() widening to size_t: the
local that catches its return needs to be size_t too, otherwise the
widening would introduce a silent Windows narrowing here. No
semantic effect with the current unsigned-long-returning
git_deflate_bound() (size_t == unsigned long on this caller's
platforms today).

Assisted-by: Opus 4.7
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

archive-zip.c

@@ -206,7 +206,7 @@ static void *zlib_deflate_raw(void *data, unsigned long size,
 			      unsigned long *compressed_size)
 {
 	git_zstream stream;
-	unsigned long maxsize;
+	size_t maxsize;
 	void *buffer;
 	int result;