ci: use Ubuntu shfmt shell formatter

[MikeMcC399]

• closes Outdated Docker image peterdavehello/shfmt:2.6.3 in shfmt.yml #2555

Description

• Replace custom Docker image peterdavehello/shfmt:2.6.3 in .github/workflows/shfmt.yml with Ubuntu package shfmt for shell script format linting.

• Use shfmt -d for read-only --diff linting in CI.

Motivation and Context

peterdavehello/shfmt:2.6.3 in .github/workflows/shfmt.yml was published in Jan 2019 and is outdated.

Ubuntu offers the package shfmt which relieves the need for a specially built Docker image to perform shell script linting in CI. It is also available in Debian. See https://github.com/mvdan/sh.

Testing Details

Locally in Ubuntu 24.04.4 LTS, execute:

sudo apt-get update
sudo apt-get install -y shfmt
shfmt -sr -i 2 -l -w -ci -d .

and confirm no error reported.

Check for success of job shfmt in workflow .github/workflows/shfmt.yml

Types of changes

• Documentation
• Version change (Update, remove or add more Node.js versions)
• Variant change (Update, remove or add more variants, or versions of variants)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Other (none of the above)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• All new and existing tests passed.

[MikeMcC399]

@PeterDaveHello

Please review, as it replaces your special Docker image for checking shell scripts and uses instead the standard package from Ubuntu.