chore(deps): Update dependencies

[reneleonhardt]

⬆️ Updates

• Update to Go 1.21 (oldest supported version)
• Test with Go 1.21 and 1.22
• Update dependencies
• Update semaphore to ubuntu2204
• Migrate deprecated ioutil
• Migrate superseeded gometalinter to golangci-lint

🐛 Fixes

• Fix security vulnerability

Library	Vulnerability	Severity
golang.org/x/net	CVE-2023-45288	MEDIUM

👷 sem-version does not what you think it does... 😅

• Watch out: semaphore's sem-version is very different from GitHub Actions, 1.21 fetches the oldest 1.21.0, not the latest 1.21.12
• Unfortunately the documentation omits this little detail in the example... https://docs.semaphoreci.com/ci-cd-environment/sem-version-managing-language-versions-on-linux/