Update Rust crate schemars to v1.2.1 (#17924)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [schemars](https://graham.cool/schemars/)
([source](https://redirect.github.com/GREsau/schemars)) |
workspace.dependencies | patch | `1.2.0` → `1.2.1` |

---

### Release Notes

<details>
<summary>GREsau/schemars (schemars)</summary>

###
[`v1.2.1`](https://redirect.github.com/GREsau/schemars/blob/HEAD/CHANGELOG.md#121---2026-02-01)

[Compare
Source](https://redirect.github.com/GREsau/schemars/compare/v1.2.0...v1.2.1)

##### Fixed

- `transform` attributes are now applied after the schema is otherwise
fully constructed. In particular, they're now applied after all other
attributes are processed.
([#&#8203;505](https://redirect.github.com/GREsau/schemars/issues/505))

</details>

---

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Cargo.lock

@@ -4195,9 +4195,9 @@ dependencies = [
 
 [[package]]
 name = "schemars"
-version = "1.2.0"
+version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "54e910108742c57a770f492731f99be216a52fadd361b06c8fb59d74ccc267d2"
+checksum = "a2b42f36aa1cd011945615b92222f6bf73c599a102a300334cd7f8dbeec726cc"
 dependencies = [
  "dyn-clone",
  "ref-cast",
@@ -4209,9 +4209,9 @@ dependencies = [
 
 [[package]]
 name = "schemars_derive"
-version = "1.2.0"
+version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4908ad288c5035a8eb12cfdf0d49270def0a268ee162b75eeee0f85d155a7c45"
+checksum = "7d115b50f4aaeea07e79c1912f645c7513d81715d0420f8bc77a18c6260b307f"
 dependencies = [
  "proc-macro2",
  "quote",