py3: use `zip()` instead of trying to use `itertools.izip()`

py3: use `zip()` instead of trying to use `itertools.izip()`

--- a/tests/test-manifest.py	Sun May 29 15:33:39 2022 +0200
+++ b/tests/test-manifest.py	Sun May 29 15:38:01 2022 +0200
@@ -58,12 +58,10 @@
 
 HUGE_MANIFEST_ENTRIES = 200001
 
-izip = getattr(itertools, 'izip', zip)
-
 A_HUGE_MANIFEST = b''.join(
     sorted(
         b'file%d\0%s%s\n' % (i, h, f)
-        for i, h, f in izip(
+        for i, h, f in zip(
             range(200001),
             itertools.cycle((HASH_1, HASH_2)),
             itertools.cycle((b'', b'x', b'l')),