build(deps): bump submodules/rest-api-specs from 4e38204 to `c68421…

…b` (#4529)

Bumps [submodules/rest-api-specs](https://github.com/Azure/azure-rest-api-specs) from `4e38204` to `c68421b`.
- [Release notes](https://github.com/Azure/azure-rest-api-specs/releases)
- [Commits](Azure/azure-rest-api-specs@4e38204...c68421b)

---
updated-dependencies:
- dependency-name: submodules/rest-api-specs
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>