Backport PR #48398 on branch 1.5.x (WARN: Avoid FutureWarnings in tes…

…ts) (#48420)

* Backport PR #48398: WARN: Avoid FutureWarnings in tests

* Update

Co-authored-by: Patrick Hoefler <61934744+phofl@users.noreply.github.com>
Co-authored-by: Marc Garcia <garcia.marc@gmail.com>

pandas/tests/frame/methods/test_fillna.py

@@ -777,6 +777,6 @@ def test_fillna_nonconsolidated_frame():
         ],
         columns=["i1", "i2", "i3", "f1"],
     )
-    df_nonconsol = df.pivot("i1", "i2")
+    df_nonconsol = df.pivot(index="i1", columns="i2")
     result = df_nonconsol.fillna(0)
     assert result.isna().sum().sum() == 0