Support RxJS v7

[wSedlacek]

Description

RxJS 6 and 7 is supported by Angular 13

Proposed solution

• Change RxJS dependency to be '^6.0.0 || ^7.0.0`
• Update any removed APIs with ones that are compatible with v6
• Do not use any new ^7.0.0 APIs until Angular has dropped support for RxJS 6 altogether

Alternatives considered

Update to only support ^7.0.0 which would allow usage of the new APIs at the cost of having support misaligned with Angular

Do you want to create a pull request?

Yes

[wSedlacek]

🤔 After looking at the code it seems that rxjs is not intended to be a dependency of reactive-forms at all.

When I build the package with nx build reactive-forms I get the follow peer dependencies.

  "peerDependencies": {
    "@angular/forms": ">= 13.0.0",
    "@angular/core": "13.0.2"
  },

However when I install the package from npm it has the following dependencies.

  "peerDependencies": {
    "@angular/forms": ">= 13.0.0",
    "rxjs": "~6.6.0",
    "@angular/core": "13.0.2"
  },

This is interesting because the only commit since the 4.0.0 commit was
3adcf11

Perhaps this is an issue of an outdated nx CLI being used to build and publish?
Or perhaps there is some dependency cache going on the CI?