Update anthropic.mdx (#18992)

got rid of extra backtick

Author: kathayl

src/content/docs/ai-gateway/providers/anthropic.mdx

@@ -8,7 +8,7 @@ pcx_content_type: get-started
 ## Endpoint
 
 ```txt
-https://gateway.ai.cloudflare.com/v1/{account_id}/{gateway_id}/anthropic`
+https://gateway.ai.cloudflare.com/v1/{account_id}/{gateway_id}/anthropic
 ```
 
 ## Examples