chore(deps): upgrade rollup (#101)

* chore(deps): update devDeps for npm audit

* chore(deps): update rollup pkgs

This uses `@rollup/plugin-terser` instead of `rollup-plugin-babel` which is deprecated/unmaintained and contains security warnings.

Because these are two different minifiers, the output is slightly different (terser is, well,  _more terse_), but I've configured it so it's reasonably close to the old minified distfile.

I was only able to get to `rollup` v3.x; `rollup` v4.x requires Node.js v18.x.  We can upgrade to v4.x once we decide to drop Node.js v16.x support.