Bump protobufjs and fabric-network in /explorer/backend (#108)

Bumps [protobufjs](https://github.com/protobufjs/protobuf.js) and [fabric-network](https://github.com/hyperledger/fabric-sdk-node). These dependencies needed to be updated together.

Updates `protobufjs` from 6.11.3 to 7.2.4
- [Release notes](https://github.com/protobufjs/protobuf.js/releases)
- [Changelog](https://github.com/protobufjs/protobuf.js/blob/master/CHANGELOG.md)
- [Commits](protobufjs/protobuf.js@v6.11.3...protobufjs-v7.2.4)

Updates `fabric-network` from 2.2.14 to 2.2.18
- [Release notes](https://github.com/hyperledger/fabric-sdk-node/releases)
- [Changelog](https://github.com/hyperledger/fabric-sdk-node/blob/main/CHANGELOG.md)
- [Commits](hyperledger/fabric-sdk-node@v2.2.14...v2.2.18)

---
updated-dependencies:
- dependency-name: protobufjs
  dependency-type: indirect
- dependency-name: fabric-network
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>