fix(utils): use base64 for fromB64url util

base64url is not defined in web environment polyfills - this should result in the same thing

src/utils/base64.ts

@@ -17,7 +17,7 @@
 import { createHash } from 'crypto';
 
 export function fromB64Url(input: string): Buffer {
-  return Buffer.from(input, 'base64url');
+  return Buffer.from(input, 'base64');
 }
 
 export function toB64Url(buffer: Buffer): string {