Bump bbv from f4caa05 to c53d5b9

Bumps [bbv](https://github.com/mit-plv/bbv) from `f4caa05` to `c53d5b9`.
- [Release notes](https://github.com/mit-plv/bbv/releases)
- [Commits](mit-plv/bbv@f4caa05...c53d5b9)

---
updated-dependencies:
- dependency-name: bbv
  dependency-type: direct:production
...

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