Feature request: default to using the Anchor and Solana versions from the `Anchor.toml` file

hey, thanks for building this GitHub Action! very helpful

feature request: when no `anchor-version`/ `solana-version` are specified, it would be great if this action used the versions defined in the `Anchor.toml` file, under the `[toolchain]` settings. For example, this is what we have:

```toml
[toolchain]
  anchor_version = "0.31.1"
  solana_version = "2.2.20"
```