Bump apollo-server-core from 3.6.7 to 3.12.0 in /blockchain (#24)

Bumps [apollo-server-core](https://github.com/apollographql/apollo-server/tree/HEAD/packages/apollo-server-core) from 3.6.7 to 3.12.0.
- [Release notes](https://github.com/apollographql/apollo-server/releases)
- [Changelog](https://github.com/apollographql/apollo-server/blob/[email protected]/CHANGELOG.md)
- [Commits](https://github.com/apollographql/apollo-server/commits/[email protected]/packages/apollo-server-core)

---
updated-dependencies:
- dependency-name: apollo-server-core
  dependency-type: indirect
...

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