Warning: Unknown configuration option `write_mode`

[ci skip]
diff --git a/rustfmt.toml b/rustfmt.toml
index f24f96a..34977e4 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -1,4 +1,3 @@
 wrap_comments = true
 format_strings = true
-write_mode = "Overwrite"
 error_on_unformatted = false