build(deps): bump cacheable-request and nodemon in /backend

Removes [cacheable-request](https://github.com/jaredwray/cacheable-request). It's no longer used after updating ancestor dependency [nodemon](https://github.com/remy/nodemon). These dependencies need to be updated together.


Removes `cacheable-request`

Updates `nodemon` from 2.0.6 to 2.0.20
- [Release notes](https://github.com/remy/nodemon/releases)
- [Commits](remy/nodemon@v2.0.6...v2.0.20)

---
updated-dependencies:
- dependency-name: cacheable-request
  dependency-type: indirect
- dependency-name: nodemon
  dependency-type: direct:development
...

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