chore: bump MSRV to 1.90

[alvarowolfx]

It is more than a year since 1.88 and 1.89 turns 1 year old next Friday. So jumping to 1.90 as MSRV.

There is still a extract_if() cleanup to do in PubSub, but will leave for a separated PR.

[gemini-code-assist]

Code Review

This pull request updates the Minimum Supported Rust Version (MSRV) from 1.88 to 1.90 across the repository, including documentation, Cargo.toml, and CI configurations. It also introduces a dedicated Google Cloud Build configuration for MSRV testing. Feedback points out a potential issue in the Terraform trigger configuration where removing the rust_version attribute could lead to an empty string overriding the default MSRV in Cloud Build, potentially causing build failures. A suggestion is provided to filter out null values in the Terraform substitutions map.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.25%. Comparing base (0fe6840) to head (2b5dc01).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6291      +/-   ##
==========================================
- Coverage   96.25%   96.25%   -0.01%     
==========================================
  Files         283      283              
  Lines       72936    72936              
==========================================
- Hits        70204    70203       -1     
- Misses       2732     2733       +1     

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[coryan]

The trigger is still using the 1.88 docker image. You need to manually update the trigger first (using the old school method) and then send this PR.

[coryan]

And then update the trigger again to use the new msrv.yaml file.

[alvarowolfx]

yeah, make sense. I was afraid of pushing the terraform updates and breaking other PR CI checks in the meantime while this PR is not merged. Will sync with the team to do so.