use consistent naming in test

Author: matiaslindgren

pandas/tests/indexing/multiindex/test_multiindex.py

@@ -273,10 +273,10 @@ def test_multiindex_assign_aligns_as_implicit_tuple(self):
         tm.assert_frame_equal(df1, df3)
 
         # GH 62518
-        meta = DataFrame(
+        df4 = DataFrame(
             columns=MultiIndex.from_arrays(
                 [["a", "a", "z", "z"], pd.Categorical([1, 2, 1, 2])],
             ),
             dtype=object,
         )
-        meta["z"] = meta["z"].astype("int64")
+        df4["z"] = df4["z"].astype("int64")