Bump arc-swap from 0.4.7 to 0.4.8

Bumps [arc-swap](https://github.com/vorner/arc-swap) from 0.4.7 to 0.4.8.
- [Release notes](https://github.com/vorner/arc-swap/releases)
- [Changelog](https://github.com/vorner/arc-swap/blob/v0.4.8/CHANGELOG.md)
- [Commits](vorner/arc-swap@v0.4.7...v0.4.8)

---
updated-dependencies:
- dependency-name: arc-swap
  dependency-type: indirect
...

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