chore(deps): update golan from 1.25.7 to 1.26.1

[jzirkelbach]

Resolving the following vulnerabilities:

name           severity publish_date resource version fix_version
----           -------- ------------ -------- ------- -----------
CVE-2026-27142 high     2026-03-06   stdlib   1.25.7  1.25.8, 1.26.1
CVE-2026-25679 high     2026-03-06   stdlib   1.25.7  1.25.8, 1.26.1

This pull request updates the project to use Go version 1.26.1 across all relevant configuration files and workflows. This ensures consistency in the development environment and CI/CD pipelines.

Go version upgrade:

• Updated the Go version from 1.25.7 to 1.26.1 in the Dockerfile, ensuring the development image uses the latest version.
• Updated the Go version in the go.mod file to 1.26.1 to reflect the project's required Go version.

CI/CD workflow updates:

• Updated the Go version to 1.26.1 in the relativity-ci.yml GitHub Actions workflow.
• Updated the Go version to 1.26.1 in the release.yaml GitHub Actions workflow.