Upgrade some more dev dependencies (#505)

* Upgrade chai a bit

* Bump rollup one major version (doesn't break anything yet)

* Bump rollup to 3.0.0 and tweak stuff to make the error messages go away

* Bump rollup to latest

Author: ExplodingCabbage

package.json

@@ -78,7 +78,7 @@
     "karma-sourcemap-loader": "^0.4.0",
     "karma-webpack": "^5.0.1",
     "mocha": "^6.0.0",
-    "rollup": "^1.0.2",
+    "rollup": "^4.13.0",
     "rollup-plugin-babel": "^4.2.0",
     "semver": "^7.6.0",
     "webpack": "^5.90.3",

rollup.config.js renamed to rollup.config.mjs

@@ -1,5 +1,5 @@
 import babel from 'rollup-plugin-babel';
-import pkg from './package.json';
+import pkg from './package.json' assert { type: 'json' };
 
 export default [
   // browser-friendly UMD build