chore(deps): bump syn from 1.0.103 to 1.0.104

Bumps [syn](https://github.com/dtolnay/syn) from 1.0.103 to 1.0.104.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](dtolnay/syn@1.0.103...1.0.104)

---
updated-dependencies:
- dependency-name: syn
  dependency-type: indirect
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>