build(deps): bump syn from 1.0.48 to 1.0.50
Bumps [syn](https://github.com/dtolnay/syn) from 1.0.48 to 1.0.50.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](https://github.com/dtolnay/syn/compare/1.0.48...1.0.50)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>