Add minimum Python version to readme.

Author: codeofdusk

README.md

@@ -2,7 +2,7 @@
 Gptcmd allows you to interact with OpenAI's chat-based models (`gpt-3.5-turbo` and, if available to you, `gpt-4`) efficiently in your terminal. Gptcmd can manage multiple concurrent "threads" of conversation, allowing for free and easy prompt experimentation and iteration. Individual messages can be manipulated, loaded from, and saved to files (both plain text and JSON), and API parameters are fully customizable. In short, Gptcmd is simple yet flexible, useful for both basic conversation and more involved prototyping.
 
 ## Getting started
-Gptcmd is available on PyPI, and can, for instance, be installed with `pip install gptcmd` at a command line shell. Running `gptcmd` at a shell starts the application. If Python's `bin` or `scripts` directory isn't on your path, you may need to launch the application with a command like `~/.local/bin/gptcmd` (depending on your system configuration). In most cases though, `gptcmd` should "just work".
+Gptcmd requires [Python](https://python.org) 3.7.1 or later. It is available on PyPI, and can, for instance, be installed with `pip install gptcmd` at a command line shell. Running `gptcmd` at a shell starts the application. If Python's `bin` or `scripts` directory isn't on your path, you may need to launch the application with a command like `~/.local/bin/gptcmd` (depending on your system configuration). In most cases though, `gptcmd` should "just work".
 
 Gptcmd searches for an OpenAI API key in the `OPENAI_API_KEY` environment variable. If no key was found, Gptcmd will ask for it at launch. If you don't have an API key, you'll need to create an OpenAI account if you don't have one, then [generate a key](https://beta.openai.com/account/api-keys).