Update to rust 1.84. (#392)

This is the latest stable rust toolchain.
I had to run `cargo update` as some of the older
deps did not support latest rust.

I noticed a dependabot PR failed regarding a rust version mismatch:
#391

I'm not sure this will fix it, but it seems like a good step anyways.

---

I also changed the github action to explicity use ubuntu 22 instead of `latest`.
`latest` recently changed to ubuntu 24:

https://github.blog/changelog/2024-09-25-actions-new-images-and-ubuntu-latest-changes/

This fixes the following test failure

```
---- repo_version::tests::test_run_python_script stdout ----
thread 'repo_version::tests::test_run_python_script' panicked at ops/src/repo_version.rs:392:55:
called `Result::unwrap()` on an `Err` value: Error running version script (exit code 1; script: python version.py):

Access error: uid 1001, last mount name:/firejail/firejail.ro.file dir:/run/firejail/firejail.ro.file type:tmpfs - invalid noexec mount

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

This may be related to sanbox changes in ubuntu 24:

- bazelbuild/bazel#24081
- https://ubuntu.com/blog/ubuntu-23-10-restricted-unprivileged-user-namespaces

--- 

Run cargo clippy --fix to fix a bunch of new warnings, and manually fix the rest.

Author: rcorre

Diff for: .github/workflows/rust.yml

@@ -5,7 +5,7 @@ on: [push]
 jobs:
   build:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
 
     steps:
     - name: Checkout sources
@@ -24,7 +24,7 @@ jobs:
       uses: actions-rs/toolchain@v1
       with:
         profile: minimal
-        toolchain: 1.73.0
+        toolchain: 1.84.0
         override: true
         components: rustfmt, clippy