Remove deprecated install input from setup-buildx-action

[skypank-coder]

Summary:

closes #1729

Removed the install: true input from the docker/setup-buildx-action step in pull_request.yaml, push.yaml, and release.yaml. These workflows pin setup-buildx-action at v4.1.0, where the install input no longer exists, so passing it produced the "Unexpected input(s) 'install'" warning across the PR, CI, and release pipelines. The input was unused here — the build steps run through docker/build-push-action and select the builder explicitly via builder: ${{ steps.buildx.outputs.name }} — so removing it is behavior-neutral and clears the warning.

Description for the changelog:

Remove deprecated install input from setup-buildx-action to clear the pipeline warning

Declaration:

Thanks for submitting a pull request, please make sure:

• content meets the license for this project
• appropriate unit tests have been created and/or modified
• you have considered any changes required for the functional tests
• you have read the contribution guide and agree to the Code of Conduct
• either no AI-generated content has been used in this pull request
• or any use of AI in this pull request has been disclosed below:

Other info:

This is a CI configuration change only; no application code is affected, so no unit or functional test changes apply. Verification is that the PR, push, and release pipelines run without the buildx warning, visible in this PR's Actions run.

[jgadsden]

Hello @skypank-coder , please refer to the contributing guidelines, in particular to the section on pull requests

[skypank-coder]

@jgadsden Thanks — updated the PR to use the template with the declaration filled in."