chore: package.json cleanup (#1648)

Author: mdjastrzebski

package.json

@@ -26,18 +26,13 @@
     "clean": "del build",
     "test": "jest",
     "test:ci": "jest --maxWorkers=2 --collectCoverage=true --coverage-provider=v8",
-    "test:react-17": "scripts/test_react_17",
     "typecheck": "tsc",
-    "flow": "flow",
     "copy-flowtypes": "cp typings/index.flow.js build",
     "lint": "eslint src --cache",
     "validate": "yarn lint && yarn typecheck && yarn test",
     "build:js": "babel src --out-dir build --extensions \".js,.ts,.jsx,.tsx\" --source-maps --ignore \"**/__tests__/**\"",
-    "build:js:watch": "yarn build:js --watch",
     "build:ts": "tsc --build tsconfig.release.json",
-    "build:ts:watch": "yarn build:ts --watch --preserveWatchOutput",
     "build": "yarn clean && yarn build:js && yarn build:ts && yarn copy-flowtypes",
-    "prepare": "yarn build",
     "prepublish": "yarn build",
     "publish": "release-it"
   },