fix buffer import and use rollup for transpiling the package.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "nostr-tools",
-  "version": "0.6.3",
+  "version": "0.6.1",
   "description": "Tools for making a Nostr client.",
   "main": "dist/nostr-tools.esm.min.js",
   "module": "dist/nostr-tools.esm.min.js",
@@ -30,6 +30,9 @@
   "devDependencies": {
     "rollup": "^2.61.1"
   },
+  "files": [
+    "dist"
+  ],
   "scripts": {
     "prepublish": "rollup -c"
   }

rollup.config.js

@@ -1,7 +1,7 @@
 import pkg from './package.json'
 
 export default {
-  input: 'index.js',
+  input: 'src/index.js',
   output: [
     {
       name: 'nostrtools',