babel Конфигурация в package.json без .babelrc

Просто используйте секцию с тем же именем, например:

{
    "name": "js-wrapper-lib",
    "version": "1.0.7",
    "description": "js functions wrappers library",
    "main": "./dist/jswl.js",
    "scripts": {
        "test": "jest",
        "build": "webpack --config webpack.config.js",
        "watch": "webpack --watch --mode=development"
    },
    "devDependencies": {
        "@babel/plugin-transform-modules-commonjs": "^7.8.3",
        "jest": "^24.9.0",
        "webpack": "^4.28.4",
        "webpack-cli": "^3.2.1"
    },
    "repository": {
        "type": "git"
    },
    "keywords": [
        "javascript",
        "library"
    ],
    "babel": {
        "env": {
            "test": {
                "plugins": [
                    "@babel/plugin-transform-modules-commonjs"
                ]
            }
        }
    },
    "author": "it-for-free",
    "license": "MIT"
}