Remove actions-rs/toolchain, cache dependencies

[simonmarty]

Description

https://github.com/actions/cache/blob/main/examples.md#rust---cargo

Why is this change being made?

1. actions-rs/toolchain is no longer maintained and still on Node 20.
2. The cargo-deny step takes a long time because it has to fetch the dependencies, even if Cargo.lock has not changed since the last execution.

What is changing?

1. Replace actions-rs/toolchain with rustup commands. rustup is provided on the GitHub hosted runners.
2. Cache rust dependencies and build artifacts on a hash of the Cargo.lock file.

Related Links

• Issue #, if available:

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Testing

How was this tested?

1. Tested on fork, reduces consecutive build times from 23 minutes to 3 minutes on Windows (the slowest build target).

When testing locally, provide testing artifact(s):

1. First run: https://github.com/simonmarty/aws-secretsmanager-agent/actions/runs/23924128450
2. Second run: https://github.com/simonmarty/aws-secretsmanager-agent/actions/runs/23926285140

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Reviewee Checklist

Update the checklist after submitting the PR

• I have reviewed, tested and understand all changes
  If not, why:
• I have filled out the Description and Testing sections above
  If not, why:
• Build and Unit tests are passing
  If not, why:
• Unit test coverage check is passing
  If not, why:
• Integration tests pass locally
  If not, why:
• I have updated integration tests (if needed)
  If not, why:
• I have ensured no sensitive information is leaking (i.e., no logging of sensitive fields, or otherwise)
  If not, why:
• I have added explanatory comments for complex logic, new classes/methods and new tests
  If not, why:
• I have updated README/documentation (if needed)
  If not, why:
• I have clearly called out breaking changes (if any)
  If not, why:

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Reviewer Checklist

All reviewers please ensure the following are true before reviewing:

• Reviewee checklist has been accurately filled out
• Code changes align with stated purpose in description
• Test coverage adequately validates the changes

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.14%. Comparing base (2053c88) to head (8a9e036).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #187   +/-   ##
=======================================
  Coverage   92.14%   92.14%           
=======================================
  Files          14       14           
  Lines        2405     2405           
  Branches     2405     2405           
=======================================
  Hits         2216     2216           
  Misses        143      143           
  Partials       46       46           

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[madsid]

LGTM!