Adjust rollup config for peer dep on preserves

packages/core/rollup.config.js

@@ -5,13 +5,16 @@ import { SyndicateRollup } from '../../rollup.js';
 const r = new SyndicateRollup('syndicate', { globalName: 'Syndicate' });
 export default [
   r.config('lib/index.js', r.umd, {
+    external: ['@preserves/core', 'crypto'],
     output: {
       globals: {
         'crypto': 'crypto',
+        '@preserves/core': 'Preserves',
       },
     },
   }),
   r.config('lib/index.js', r.es6, {
+    external: ['@preserves/core'],
     resolve: {
       moduleDirectories: ['stubs', 'node_modules'],
     },