Update CI for SGX SDK action update

[nick-mobilecoin]

Also update the rust toolchain action to https://github.com/dtolnay/rust-toolchain

Motivation

Future Work

[nick-mobilecoin]

Current dependencies on/for this PR:

• main
  • PR Update CI for SGX SDK action update #14 👈
    • PR Move panic to panic/abort #13
      • PR Add untrusted side of stderr from enclave #15
        • PR Add mc-sgx-io #22
          • PR Add mc-sgx-panic-log #24
            • PR Add mc-sgx-panic crate for common panic handling #30
              • PR Add panicking::panic_count to mc-sgx-panic #31
                • PR Update CODEOWNERS file #32
                  • PR Add panicking::panicking() function #33
                  • PR Add public function thread::panicking() #34
                  • PR Add mc-sgx-sync crate #35
                  • PR Add poison.rs to mc-sgx-sync crate #36
                  • PR Add sys module to mc-sgx-sync #39
                  • PR Add mutex.rs to mc-sgx-sync crate #40
                  • PR Use a static buffer for panic messages #41
                  • PR Add mc-sgx-sync::sys::locks::Condvar #42
                  • PR Add Condvar to mc-sgx-sync crate #43
                  • PR Add mc-sgx-sync::sys::locks::RwLock #44
                  • PR Add RwLock to mc-sgx-sync #45
                  • PR Add example usage for mc-sgx-sync and std::sync #46
                  • PR Merge panic-abort and panic-log crates into mc-sgx-panic #48
                  • PR Prevent recursive panics from happening #50
                  • PR Remove unneeded traits on sys types #51
        • PR Rename mc-sgx-io to mc-sgx-io-untrusted #21

This comment was auto-generated by Graphite.

[jcape]

Mostly LGTM, but we should always use rust-toolchain@master with a strategy matrix, because:

1. I don't think there are tags for each nightly
2. The rust-toolchain action doesn't change the default, so even rust-toolchain@nightly (which does exist) requires one to also do cargo +nightly foo at every invocation.