move bundlesize to dev dep

package.json

@@ -61,7 +61,6 @@
   "homepage": "https://styled-components.com",
   "dependencies": {
     "buffer": "^5.0.3",
-    "bundlesize": "^0.5.5",
     "css-to-react-native": "^2.0.3",
     "fbjs": "^0.8.9",
     "hoist-non-react-statics": "^1.2.0",
@@ -88,6 +87,7 @@
     "babel-plugin-transform-react-remove-prop-types": "^0.4.1",
     "babel-preset-env": "^1.4.0",
     "babel-preset-react": "^6.22.0",
+    "bundlesize": "^0.5.5",
     "chokidar": "^1.6.0",
     "danger": "^0.16.0",
     "enzyme": "^2.8.2",

yarn.lock

@@ -1237,7 +1237,7 @@ builtin-modules@^1.0.0, builtin-modules@^1.1.0, builtin-modules@^1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/builtin-modules/-/builtin-modules-1.1.1.tgz#270f076c5a72c02f5b65a47df94c5fe3a278892f"
 
-[email protected]:
+bundlesize@^0.5.5:
   version "0.5.5"
   resolved "https://registry.yarnpkg.com/bundlesize/-/bundlesize-0.5.5.tgz#7fd2d34cf78aeb4fe250e01c6d71f027e3e01893"
   dependencies: