chore(deps): bump verification/cbmc/aws-c-common

Bumps [verification/cbmc/aws-c-common](https://github.com/awslabs/aws-c-common) from `70ed84b` to `6d974f9`.
- [Release notes](https://github.com/awslabs/aws-c-common/releases)
- [Commits](awslabs/aws-c-common@70ed84b...6d974f9)

---
updated-dependencies:
- dependency-name: verification/cbmc/aws-c-common
  dependency-type: direct:production
...

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