[Snyk] Security upgrade golang from 1.16-alpine to 1.21.9-alpine

[spresser-hlrs]

This PR was automatically created by Snyk using the credentials of a real user.

Keeping your Docker base image up-to-date means you’ll benefit from security fixes in the latest version of your chosen image. #### Changes included in this PR - docker/Dockerfile We recommend upgrading to `golang:1.21.9-alpine`, as this image has only 1 known vulnerabilities. To do this, merge this pull request, then verify your application still works as expected. Some of the most important vulnerabilities in your base image include: | Severity | Priority Score / 1000 | Issue | Exploit Maturity | | :------: | :-------------------- | :---- | :--------------- | |  | **614** | CVE-2022-28391
[SNYK-ALPINE315-BUSYBOX-2440607](https://snyk.io/vuln/SNYK-ALPINE315-BUSYBOX-2440607) | No Known Exploit | |  | **614** | CVE-2022-28391
[SNYK-ALPINE315-BUSYBOX-2440607](https://snyk.io/vuln/SNYK-ALPINE315-BUSYBOX-2440607) | No Known Exploit | |  | **614** | Loop with Unreachable Exit Condition ('Infinite Loop')
[SNYK-ALPINE315-LIBRETLS-2428776](https://snyk.io/vuln/SNYK-ALPINE315-LIBRETLS-2428776) | No Known Exploit | |  | **614** | Access of Resource Using Incompatible Type ('Type Confusion')
[SNYK-ALPINE315-OPENSSL-3314622](https://snyk.io/vuln/SNYK-ALPINE315-OPENSSL-3314622) | No Known Exploit | |  | **714** | Out-of-bounds Write
[SNYK-ALPINE315-ZLIB-2976173](https://snyk.io/vuln/SNYK-ALPINE315-ZLIB-2976173) | No Known Exploit | --- **Note:** _You are seeing this because you or someone else with access to this repository has authorized Snyk to open fix PRs._ For more information: 🧐 [View latest project report](https://app.snyk.io/org/spresser-hlrs/project/c7fc3ca3-8d59-453d-9a53-af93b2e70812?utm_source=github&utm_medium=referral&page=fix-pr) 🛠 [Adjust project settings](https://app.snyk.io/org/spresser-hlrs/project/c7fc3ca3-8d59-453d-9a53-af93b2e70812?utm_source=github&utm_medium=referral&page=fix-pr/settings) [//]: # 'snyk:metadata:{"prId":"ec426b50-255c-48ce-b1d7-6c0c40f9debf","prPublicId":"ec426b50-255c-48ce-b1d7-6c0c40f9debf","dependencies":[{"name":"golang","from":"1.16-alpine","to":"1.21.9-alpine"}],"packageManager":"dockerfile","projectPublicId":"c7fc3ca3-8d59-453d-9a53-af93b2e70812","projectUrl":"https://app.snyk.io/org/spresser-hlrs/project/c7fc3ca3-8d59-453d-9a53-af93b2e70812?utm_source=github&utm_medium=referral&page=fix-pr","type":"auto","patch":[],"vulns":["SNYK-ALPINE315-ZLIB-2976173","SNYK-ALPINE315-OPENSSL-3314622","SNYK-ALPINE315-BUSYBOX-2440607","SNYK-ALPINE315-LIBRETLS-2428776"],"upgrade":["SNYK-ALPINE315-BUSYBOX-2440607","SNYK-ALPINE315-BUSYBOX-2440607","SNYK-ALPINE315-LIBRETLS-2428776","SNYK-ALPINE315-OPENSSL-3314622","SNYK-ALPINE315-ZLIB-2976173"],"isBreakingChange":false,"env":"prod","prType":"fix","templateVariants":["updated-fix-title","priorityScore"],"priorityScoreList":[714,614,614,614],"remediationStrategy":"vuln"}' --- **Learn how to fix vulnerabilities with free interactive lessons:** 🦉 [Access of Resource Using Incompatible Type ('Type Confusion')](https://learn.snyk.io/lesson/type-confusion/?loc=fix-pr)

[sonarcloud[bot]]

Quality Gate failed

Failed conditions
1 Security Hotspot
D Maintainability Rating on New Code (required ≥ A)

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