Update terser dependency

[DillonSadofsky]

We are using this plugin plus the rollup-terser-plugin in a couple projects, and in a newer one we started targeting a newer version of ECMA in the output, which lead to some more modern JS features remaining in the js during transpile (for example optional chaining). This choked up rollup-plugin-terser, but updating it fixed it. However, when I use rollup-plugin-size-snapshot, it dies on line 80 because of line 68:

      const minified = (0, _terser.minify)(source).code;

returns undefined due to modern ECMA symbols breaking the version of the terser included as a dependency:

If it doesn't break anything, it'd be nice to see the terser as a peer dependency or just updated to support modern js features.