Fix typo in code comments: "anount" -> "amount" (#1297)

## Summary

Fix typo `anount` -> `amount` in comments within `update()` and
`merge()`.

## Test plan

- Comment-only change, no behavioral impact

Author: veeceey

multidict/_multidict_py.py

@@ -993,7 +993,7 @@ def update(self, arg: MDArg[_V] = None, /, **kwargs: _V) -> None:
         log2_size = estimate_log2_keysize(newsize)
         if log2_size > 17:  # pragma: no cover
             # Don't overallocate really huge keys space in update,
-            # duplicate keys could reduce the resulting anount of entries
+            # duplicate keys could reduce the resulting amount of entries
             log2_size = 17
         if log2_size > self._keys.log2_size:
             self._resize(log2_size, False)
@@ -1044,7 +1044,7 @@ def merge(self, arg: MDArg[_V] = None, /, **kwargs: _V) -> None:
         log2_size = estimate_log2_keysize(newsize)
         if log2_size > 17:  # pragma: no cover
             # Don't overallocate really huge keys space in update,
-            # duplicate keys could reduce the resulting anount of entries
+            # duplicate keys could reduce the resulting amount of entries
             log2_size = 17
         if log2_size > self._keys.log2_size:
             self._resize(log2_size, False)