Bump CI to Rust 1.81.0

[steveluscher]

This is the latest version required by Agave 2.1.

CI is presently failing because of:

package `litemap v0.7.5` cannot be built because it requires rustc 1.81 or newer, while the currently active rustc version is 1.75.0

[changeset-bot]

⚠️ No Changeset found

Latest commit: a908b04

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[lorisleiva]

Thanks!

[lorisleiva]

Should we also bump this to 2.1?

[lorisleiva]

Famous last words.

[lorisleiva]

Ugh I just realised this was a separate PR than the web3.js update one sorry. I'll sort out this mess by making sure I've included everything that was already on the other PR.