error: use of deprecated function `deprecated_with`
 --> tests/ui/deprecated/deprecated_ser_with.rs:8:30
  |
8 |     #[serde(serialize_with = "deprecated_with")]
  |                              ^^^^^^^^^^^^^^^^^
  |
note: the lint level is defined here
 --> tests/ui/deprecated/deprecated_ser_with.rs:1:9
  |
1 | #![deny(deprecated)]
  |         ^^^^^^^^^^