chore: Update dependencies for gax

[Raphexion]

There are two main reasons for this PR.

1. There was a security problem reported in https://github.com/googleapis/elixir-google-api/pull/10753 that seems to have gone stale. This PR does the same change for gax.
2. Because the dependencies in gax are old they are preventing some newer dependencies in our project (a combination of tesla, gun, mime).

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[cblavier]

Hey 👋 will this PR be eventually merged?

[fastjames]

@dazuma would it be possible to get this pushed the rest of the way through? It would be helpful to have these dependencies updated both for security and for interoperability. It's been approved, so I'm not sure what the next step is to have it merged.