fix: dedent is a devDep of @linaria/shaker, not a prod dep

[ChALkeR]

Motivation

Remove an unsed production dep.

Summary

Like in other packages, dedent is actually a dev dep.
@linaria/babel:

linaria/packages/babel/package.json

Lines 41 to 44 in a4258f9

	"devDependencies": {
	"@types/cosmiconfig": "^5.0.3",
	"@types/dedent": "^0.7.0",
	"dedent": "^0.7.0",

@linaria/server:

linaria/packages/server/package.json

Lines 38 to 40 in a4258f9

	"devDependencies": {
	"@types/dedent": "^0.7.0",
	"dedent": "^0.7.0",

Grep output:

$ grep -r dedent packages/shaker/
packages/shaker/package.json:    "@types/dedent": "^0.7.0",
packages/shaker/package.json:    "dedent": "^0.7.0"
packages/shaker/__tests__/shaker.test.ts:import dedent from 'dedent';
packages/shaker/__tests__/shaker.test.ts:        dedent`
packages/shaker/__tests__/shaker.test.ts:        dedent`
packages/shaker/__tests__/shaker.test.ts:        dedent`

Seems to be used only in tests.

Test plan

Regular tests should pass.
I also checked that this package still works when dedent module is removed from node_modules.

[callstack-bot]

Hey @ChALkeR, thank you for your pull request 🤗.
The coverage report for this branch can be viewed here.