Update shops

Fixes #197.

content/shops.json

@@ -7,10 +7,6 @@
     "name": "Copiaro (Einundzwanzig Merch, Little HODLer, Bitcoin Hardware)",
     "url": "https://copiaro.de/einundzwanzig"
   },
-  {
-    "name": "Whitepapers",
-    "url": "http://whitepapershop.net/"
-  },
   {
     "name": "Dezentralshop (T-Shirts, Sticker, Bücher (🇨🇭Schweiz)",
     "url": "https://dezentralshop.ch/"
@@ -20,8 +16,8 @@
     "url": "https://satoshistore.io/"
   },
     {
-    "name": "Frankenstein Shop (Sticker, Caps, Hardware Wallets)",
-    "url": "https://btcfrankenstein.com/"
+    "name": "ClavaStack (Specter DIY und Specter Shield, Backup Produkte)",
+    "url": "https://clavastack.com/"
   },
   {
   "name": "Stuff4BTC (Sticker, Pins, Merch)",