Conflicting prettier configs for quotes

[bmish]

@square/prettier-config reverted to using the prettier default of double quotes in v2.0.0.

This conflicts with our configuration of prettier to use single quote:

eslint-plugin-square/lib/config/base.js

Lines 100 to 105 in 07c3e6f

	'prettier/prettier': [
	'error',
	{
	singleQuote: true,
	},
	],

and

eslint-plugin-square/lib/config/base.js

Lines 77 to 82 in 07c3e6f

	quotes: [
	'error',
	'single', // Must match quote style enforced by prettier.
	// Disallow unnecessary template literals.
	{ avoidEscape: true, allowTemplateLiterals: false },
	],

Having this conflict between our ESLint config of prettier and our non-ESLint config of prettier can cause confusion and problems as occurred here: bmish/eslint-doc-generator#283 (comment)

I'm in favor of keeping single quotes to avoid churn, so I think we need to remove or override the setting for @square/prettier-config.

@maxbeatty

[maxbeatty]

easiest thing to do is pin to v1 of @square/prettier-config and keep using single quotes. the shared configs rarely ever change and are so minimal they should continue to work with prettier (🤞🏼). if something does come up, it wouldn't be too much trouble to maintain both majors similar to Node's strategy.