Tslib dependency at runtime

[mbiegert]

This seems to be somewhat of a followup to #849. There the issue was supposedly fixed with adding tslib to the dependencies. However it was added to the "devDependencies", however it appears to should have been added to the regular "dependencies" list. When using the pnp mode of yarn in my project which depends on "@nestjs-modules/mailer@^2.0.2" I receive the following error on starting nest:

Error: @nestjs-modules/mailer tried to access tslib, but it isn't declared in its dependencies; this makes the require call ambiguous and unsound.

The following yarn packageExtension fixes this:

  "@nestjs-modules/mailer@^2.0.0": {
    dependencies: {
      # This is the version of tslib they declare in their devDependencies
      tslib: "2.6.2"
    }
  }