deprecation message with `chat_github()`

[simonpcouch]

When running chat_github() with no arguments, I see an argument deprecation message re: chat_openai(seed)

ellmer::chat_github()
#> Using model = "gpt-4o".
#> Warning: The `seed` argument of `chat_openai()` is deprecated as of ellmer 0.2.0.
#> ℹ Please use the `params` argument instead.
#> ℹ The deprecated feature was likely used in the ellmer package.
#>   Please report the issue at <https://github.com/tidyverse/ellmer/issues>.
#> This warning is displayed once every 8 hours.
#> Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
#> generated.
#> <Chat OpenAI/gpt-4o turns=0 tokens=0/0 $0.00>

^{Created on 2025-06-16 with reprex v2.1.1}

Seen with 0.2.1 and main.