Upgrade Go version to 1.26.1

[github-actions]

Upgrade Go version to 1.26.1:
https://go.dev/doc/devel/release

• Set PR as "Ready for review"
• Check CI
• Submit PR review

[github-actions]

Overview

Image reference	score-radius:latest	score-radius:latest
- digest	9b432bf0a685	361afb6c87b5
- tag	latest	latest
- provenance	fbb1d2f	2132b22
- vulnerabilities
- platform	linux/amd64	linux/amd64
- size	5.4 MB	5.4 MB (+160 B)
- packages	40	40

Policies (0 improved, 0 worsened)

Policy Name	score-radius:latest	score-radius:latest	Change	Standing
Default non-root user	✅	✅		No Change
No AGPL v3 licenses	✅	✅		No Change
No fixable critical or high vulnerabilities	✅	✅		No Change
No high-profile vulnerabilities	✅	✅		No Change
No outdated base images	✅	✅		No Change
No unapproved base images	✅	✅		No Change
Supply chain attestations	✅	✅		No Change
Valid Docker Hardened Image (DHI) or DHI base image	⚠️ 2	⚠️ 2		No Change

Packages and Vulnerabilities (5 package changes and 0 vulnerability changes)

• ♾️ 5 packages changed
• 35 packages unchanged

Changes for packages of type golang (5 changes)

	Package	Version score-radius:latest	Version score-radius:latest
♾️	github.com/mattn/go-runewidth	0.0.20	0.0.21
♾️	github.com/score-spec/score-go	1.12.0	1.12.1
♾️	github.com/score-spec/score-radius	0.0.0-20260308225336-fbb1d2ffe6ed+dirty	0.0.9-0.20260308225411-2132b2221e45+dirty
♾️	golang.org/x/sync	0.19.0	0.20.0
♾️	golang.org/x/sys	0.41.0	0.42.0

[mathieu-benoit]

LGTM