Add Promptmetheus to tools

Promptmetheus (https://promptmetheus.com) is an IDE to compose, test, and evaluate one-shot prompts for the OpenAI platform that predictably transform input to output.

Author: toniengelhardt

pages/tools.mdx

@@ -30,6 +30,7 @@
 - [Promptable](https://promptable.ai)
 - [PromptInject](https://github.com/agencyenterprise/PromptInject)
 - [Prompts.ai](https://github.com/sevazhidkov/prompts-ai)
+- [Promptmetheus](https://promptmetheus.com)
 - [PromptPerfect](https://promptperfect.jina.ai/)
 - [Promptly](https://trypromptly.com/)
 - [PromptSource](https://github.com/bigscience-workshop/promptsource)