chore: update rust toolchain to 1.94/2025-12-10

[greenhat]

This PR introduces the same changes as #12. The git tag is set to the commit and is used in 0xMiden/compiler#819

This PR can be merged ONLY after the next (v0.6) compiler release is published. Merging this PR will break the v0.5.1 released version of the compiler.

Before merging this PR set cargo-miden and miden crate dependencies to the last released versions. AND move the git tag used in cargo miden new command to that commit.

[greenhat]

@bitwalker I temporarily switched cargo-miden and miden crates to the next branch in the compiler repo until the compiler is released. To make the CI green and update this repo with the latest SDK changes.

[greenhat]

The 2300b33 sets the cargo-miden version to released 0.6.
The v0.7 git tag used in cargo miden new is moved to this commit.

[greenhat]

I checked and confirmed that released v0.6 of the cargo-miden has cargo miden new working. The previous v0.5.1 should work as well (no changes in the main branch).
So right now we have both versions working. As soon as we merge this branch v0.5.1 stops working. Let's give it some time before merging this branch so that the users upgrade to v0.6.

@bitwalker @Keinberger

[greenhat]

@Keinberger I think enough time has passed (1 month) so everyone updated their compiler to the last v0.6 released 1 month ago. Let's merge this branch in the upcoming days. This will break v0.5.1 users.