Relax Prettier dependency to ^1

[koresar]

Problem: I have several prettiers installed in my new Vue project.

How to reproduce using Vue Cli 3.

• vue init my-project
• npm ls prettier

  ├─┬ @vue/cli-service@3.0.4
  │ └─┬ vue-loader@15.4.2
  │   └─┬ @vue/component-compiler-utils@2.2.0
  │     └── prettier@1.13.7 
  ├─┬ @vue/eslint-config-prettier@3.0.4
  │ └── prettier@1.14.3  deduped
  └── prettier@1.14.3 

As you can see the @vue/component-compiler-utils dictates the (not latest) prettier version for the entire project.

[yyx990803]

1. This is intentional, because prettier has had breaking changes in minor releases in the past.

2. This does not dictate the prettier version for your entire project. As you can see from the tree, it in the worst case only causes one extra copy of prettier which is used only by this module.