chore(deps): bump mem and typescript-json-schema

Removes [mem](https://github.com/sindresorhus/mem). It's no longer used after updating ancestor dependency [typescript-json-schema](https://github.com/YousefED/typescript-json-schema). These dependencies need to be updated together.


Removes `mem`

Updates `typescript-json-schema` from 0.20.0 to 0.54.0
- [Release notes](https://github.com/YousefED/typescript-json-schema/releases)
- [Commits](YousefED/typescript-json-schema@v0.20.0...v0.54.0)

---
updated-dependencies:
- dependency-name: mem
  dependency-type: indirect
- dependency-name: typescript-json-schema
  dependency-type: direct:development
...

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Author: dependabot[bot]