fix: correct environment variable syntax in Caddyfile and clean up Docker Compose configuration

- Update Caddyfile to use correct syntax for environment variables in GoDaddy DNS settings
- Remove unnecessary version declaration from docker-compose.caddy.yml for clarity

Caddyfile

@@ -9,8 +9,8 @@
     # TLS mit DNS-01 Challenge für Wildcard
     tls {
         dns godaddy {
-            api_key {env.GODADDY_API_KEY}
-            api_secret {env.GODADDY_API_SECRET}
+            api_key {$env.GODADDY_API_KEY}
+            api_secret {$env.GODADDY_API_SECRET}
         }
     }
 
@@ -73,8 +73,8 @@
     # TLS mit DNS-01 Challenge für Wildcard
     tls {
         dns godaddy {
-            api_key {env.GODADDY_API_KEY}
-            api_secret {env.GODADDY_API_SECRET}
+            api_key {$env.GODADDY_API_KEY}
+            api_secret {$env.GODADDY_API_SECRET}
         }
     }