Use go-version-file in CI workflows instead of hardcoded Go versions

[sgaunet]

Overview

Replace hardcoded Go version strings in all GitHub Actions workflows with go-version-file: 'go.mod' to ensure CI always uses the same Go version as defined in the project.

Changes

• coverage.yml: Replace go-version: 1.24.x with go-version-file: 'go.mod'
• linter.yml: Replace go-version: stable with go-version-file: 'go.mod'
• release.yml: Replace go-version: '>=1.24' with go-version-file: 'go.mod'
• snapshot.yml: Replace go-version: '>=1.24' with go-version-file: 'go.mod'

Motivation

Single source of truth for Go version eliminates drift between CI and local development.

Branch

ci/workflows-go-version-file