Fix author url of xk6-nostr

Co-authored-by: Paul Balogh <[email protected]>

Author: akiomik

src/data/doc-extensions/extensions.json

@@ -1149,7 +1149,7 @@
       "logo": "",
       "author": {
         "name": "Akiomi Kamakura",
-        "url": "https://github.com/nostr"
+        "url": "https://github.com/akiomik"
       },
       "stars": "2",
       "type": ["JavaScript"],