ci: update version

[fluentdo-ci]

Update version

• Created by https://github.com/FluentDo/agent/actions/runs/20457683032
• Auto-generated by create-pull-request: https://github.com/peter-evans/create-pull-request

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Summary by cubic

Update FluentDo Agent to v26.1.1 across build and test configs. Dockerfiles, CMakeLists, and test scripts now default to 26.1.1 to build and validate the new release.

^{Written for commit b74a080. Summary will update automatically on new commits.}

[cubic-dev-ai]

No issues found across 6 files

[coveralls]

coverage: 56.275% (+0.002%) from 56.273%
when pulling b74a080 on ci_update-version-v26.1.1
into dedf52e on main.