Bumps [backtrace](https://github.com/rust-lang/backtrace-rs) from 0.3.48 to 0.3.49.
- [Release notes](https://github.com/rust-lang/backtrace-rs/releases)
- [Commits](rust-lang/backtrace-rs@0.3.48...0.3.49)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>