Release v1.53.1

What's Changed

• Update snapshot script results file naming so that templates with sam… by @satyakigh in #4575
• fix: Don't error on FindInMap keys resolved from parameter defaults by @kddejong in #4580
• chore(deps): bump actions/setup-python from 6 to 7 by @dependabot[bot] in #4581
• Update CloudFormation schemas to 2026-07-20 by @github-actions[bot] in #4576

Full Changelog: v1.53.0...v1.53.1