chore: replace eslint-plugin-prettier with prettier-linter-helpers

[JounQin]

Fixes #264

[JounQin]

@ikatyang Would you like help to review this PR?

---

I don't understand why we're testing node v4 on node v6?

[ikatyang]

I don't understand why we're testing node v4 on node v6?

The minimal required node version for this package is v4:

tslint-plugin-prettier/package.json

Lines 54 to 56 in 0fc2a4c

	"engines": {
	"node": ">= 4"
	},

And we cannot test node v4 directly:

tslint-plugin-prettier/.travis.yml

Lines 18 to 26 in 0fc2a4c

	- > # yarn and tslint-test do not work on node 4
	if [ "$TRAVIS_NODE_VERSION" = "6" ]; then
	echo '{ "presets": [["@babel/preset-env", { "targets": { "node": "4" } }]] }' > .babelrc.test.json
	npm install @babel/cli @babel/core @babel/preset-env
	node_modules/.bin/babel node_modules/@babel/code-frame/lib --out-dir node_modules/@babel/code-frame/lib --config-file ./.babelrc.test.json
	node_modules/.bin/babel node_modules/@babel/highlight/lib --out-dir node_modules/@babel/highlight/lib --config-file ./.babelrc.test.json
	nvm install 4
	npm run test
	fi

---

#264 (comment)

This will be a breaking change (require node 6) but it's actually just an internal change so I'll wait for other breaking changes.

[ikatyang]

Thanks!

[JounQin]

@ikatyang Any chance to publish it to npm? On tag next for example?

[ikatyang]

@JounQin Any reason you want to use it right now? As far as I can tell, there is actually no difference between prettier-linter-helpers and eslint-plugin-prettier.

[JounQin]

@ikatyang I just think it's not reasonable to have two different versions of eslint-plugin-prettier installed which may cause unexpected behavior sometimes if I'm using eslint and tslint at the same time together.

[ikatyang]

Make sense. I'll see if I have time to publish it tonight.

[ikatyang]

👉 https://github.com/prettier/tslint-plugin-prettier/releases/tag/v3.0.0-beta.0