build(deps): bump submodules/rest-api-specs from 552b4dd to 64f6997

Bumps [submodules/rest-api-specs](https://github.com/Azure/azure-rest-api-specs) from `552b4dd` to `64f6997`.
- [Release notes](https://github.com/Azure/azure-rest-api-specs/releases)
- [Commits](Azure/azure-rest-api-specs@552b4dd...64f6997)

---
updated-dependencies:
- dependency-name: submodules/rest-api-specs
  dependency-type: direct:production
...

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