Bump contracts/lib/openzeppelin-contracts-upgradeable

Bumps [contracts/lib/openzeppelin-contracts-upgradeable](https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable) from `723f8ca` to `b9cf7c9`.
- [Release notes](https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable/releases)
- [Commits](OpenZeppelin/openzeppelin-contracts-upgradeable@723f8ca...b9cf7c9)

---
updated-dependencies:
- dependency-name: contracts/lib/openzeppelin-contracts-upgradeable
  dependency-type: direct:production
...

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