fix: 🐛 postinstall script breaking on yarn v2

Author: kaisermann

Diff for: package.json

@@ -32,7 +32,7 @@
     "test:ci": "jest --silent --no-cache",
     "lint": "eslint **/*.ts",
     "format": "prettier --loglevel silent --write \"src/**/*.ts\" && eslint --fix \"src/**/*.ts\"",
-    "postinstall": "node -e \"console.log('\\u001b[36m\\u001b[1m[svelte-preprocess] Don\\'t forget to install the preprocessors packages that will be used: \\u001b[22m\\u001b[39m\\u001b[34mnode-sass/sass, stylus, less, postcss &  postcss-load-config, coffeescript, pug, etc...\\u001b[0m')\"",
+    "postinstall": "echo \"[svelte-preprocess] Don't forget to install the preprocessors packages that will be used: node-sass/sass, stylus, less, postcss & postcss-load-config, coffeescript, pug, etc...\"",
     "version": "conventional-changelog -p angular -i CHANGELOG.md -s -r 1 && git add CHANGELOG.md",
     "tag": "git tag -a v$npm_package_version -m 'Release v$npm_package_version'",
     "release": "npm run version && yarn && git add package.json yarn.lock && git commit -m \"chore(release): v$npm_package_version :tada:\"",