Bumps [webxr](https://github.com/servo/webxr) from `3e731ea` to `53c07f7`.
- [Release notes](https://github.com/servo/webxr/releases)
- [Commits](servo/webxr@3e731ea...53c07f7)

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