Try fixing Python < 3.12

Lib/fontTools/misc/iterTools.py

@@ -0,0 +1,12 @@
+from itertools import *
+
+# Python 3.12:
+if "batched" not in globals():
+    # https://docs.python.org/3/library/itertools.html#itertools.batched
+    def batched(iterable, n):
+        # batched('ABCDEFG', 3) --> ABC DEF G
+        if n < 1:
+            raise ValueError("n must be at least one")
+        it = iter(iterable)
+        while batch := tuple(islice(it, n)):
+            yield batch

Lib/fontTools/ttLib/scaleUpem.py

@@ -13,7 +13,7 @@ from fontTools.varLib import builder  # for VarData.calculateNumShorts
 from fontTools.varLib.multiVarStore import OnlineMultiVarStoreBuilder
 from fontTools.misc.vector import Vector
 from fontTools.misc.fixedTools import otRound
-from itertools import batched
+from fontTools.misc.iterTools import batched
 
 
 __all__ = ["scale_upem", "ScalerVisitor"]

Lib/fontTools/varLib/multiVarStore.py

@@ -10,7 +10,7 @@ from fontTools.varLib.builder import (
     buildMultiVarStore,
     buildMultiVarData,
 )
-from itertools import batched
+from fontTools.misc.iterTools import batched
 from functools import partial
 from collections import defaultdict
 from heapq import heappush, heappop