[Snyk] Security upgrade golang from 1.20.13 to 1.21.12

[xcaspar]

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

 ### Snyk has created this PR to fix 3 vulnerabilities in the dockerfile dependencies of this project. Keeping your Docker base image up-to-date means you’ll benefit from security fixes in the latest version of your chosen image. #### Snyk changed the following file(s): - `build/image/musl/Dockerfile` We recommend upgrading to `golang:1.21.12`, as this image has only **89** known vulnerabilities. To do this, merge this pull request, then verify your application still works as expected. #### Vulnerabilities that will be fixed with an upgrade: | | Issue | Score | :-------------------------:|:-------------------------|:-------------------------  | Information Exposure
[SNYK-DEBIAN12-GNUTLS28-6159418](https://snyk.io/vuln/SNYK-DEBIAN12-GNUTLS28-6159418) |   **614**    | Improper Input Validation
[SNYK-DEBIAN12-PYTHON311-3325304](https://snyk.io/vuln/SNYK-DEBIAN12-PYTHON311-3325304) |   **614**    | Improper Input Validation
[SNYK-DEBIAN12-PYTHON311-3325304](https://snyk.io/vuln/SNYK-DEBIAN12-PYTHON311-3325304) |   **614**    | Untrusted Search Path
[SNYK-DEBIAN12-PYTHON311-5853785](https://snyk.io/vuln/SNYK-DEBIAN12-PYTHON311-5853785) |   **614**    | Untrusted Search Path
[SNYK-DEBIAN12-PYTHON311-5853785](https://snyk.io/vuln/SNYK-DEBIAN12-PYTHON311-5853785) |   **614**   --- > [!IMPORTANT] > > - Check the changes in this PR to ensure they won't cause issues with your project. > - Max score is 1000. Note that the real score may have changed since the PR was raised. > - This PR was automatically created by Snyk using the credentials of a real user. --- **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/xcaspar/project/b5d3a997-404f-47d6-b03f-b53841227bd8?utm_source=github&utm_medium=referral&page=fix-pr) 📜 [Customise PR templates](https://docs.snyk.io/scan-using-snyk/pull-requests/snyk-fix-pull-or-merge-requests/customize-pr-templates) 🛠 [Adjust project settings](https://app.snyk.io/org/xcaspar/project/b5d3a997-404f-47d6-b03f-b53841227bd8?utm_source=github&utm_medium=referral&page=fix-pr/settings) 📚 [Read about Snyk's upgrade logic](https://support.snyk.io/hc/en-us/articles/360003891078-Snyk-patches-to-fix-vulnerabilities) --- **Learn how to fix vulnerabilities with free interactive lessons:** 🦉 [Improper Input Validation](https://learn.snyk.io/lesson/improper-input-validation/?loc=fix-pr) [//]: # 'snyk:metadata:{"customTemplate":{"variablesUsed":[],"fieldsUsed":[]},"dependencies":[{"name":"golang","from":"1.20.13","to":"1.21.12"}],"env":"prod","issuesToFix":[{"exploit_maturity":"No Known Exploit","id":"SNYK-DEBIAN12-GNUTLS28-6159418","priority_score":614,"priority_score_factors":[{"type":"fixability","label":true,"score":214},{"type":"severity","label":"high","score":400},{"type":"scoreVersion","label":"v1","score":1}],"severity":"high","title":"Information Exposure"},{"exploit_maturity":"No Known Exploit","id":"SNYK-DEBIAN12-PYTHON311-5853785","priority_score":614,"priority_score_factors":[{"type":"fixability","label":true,"score":214},{"type":"severity","label":"high","score":400},{"type":"scoreVersion","label":"v1","score":1}],"severity":"high","title":"Untrusted Search Path"},{"exploit_maturity":"No Known Exploit","id":"SNYK-DEBIAN12-PYTHON311-3325304","priority_score":614,"priority_score_factors":[{"type":"fixability","label":true,"score":214},{"type":"severity","label":"high","score":400},{"type":"scoreVersion","label":"v1","score":1}],"severity":"high","title":"Improper Input Validation"},{"exploit_maturity":"No Known Exploit","id":"SNYK-DEBIAN12-PYTHON311-3325304","priority_score":614,"priority_score_factors":[{"type":"fixability","label":true,"score":214},{"type":"severity","label":"high","score":400},{"type":"scoreVersion","label":"v1","score":1}],"severity":"high","title":"Improper Input Validation"},{"exploit_maturity":"No Known Exploit","id":"SNYK-DEBIAN12-PYTHON311-5853785","priority_score":614,"priority_score_factors":[{"type":"fixability","label":true,"score":214},{"type":"severity","label":"high","score":400},{"type":"scoreVersion","label":"v1","score":1}],"severity":"high","title":"Untrusted Search Path"}],"prId":"2dd8bf05-caab-4120-a6c4-ff46f7600b62","prPublicId":"2dd8bf05-caab-4120-a6c4-ff46f7600b62","packageManager":"dockerfile","priorityScoreList":[614,614,614],"projectPublicId":"b5d3a997-404f-47d6-b03f-b53841227bd8","projectUrl":"https://app.snyk.io/org/xcaspar/project/b5d3a997-404f-47d6-b03f-b53841227bd8?utm_source=github&utm_medium=referral&page=fix-pr","prType":"fix","templateFieldSources":{"branchName":"default","commitMessage":"default","description":"default","title":"default"},"templateVariants":["updated-fix-title","priorityScore"],"type":"auto","upgrade":["SNYK-DEBIAN12-GNUTLS28-6159418","SNYK-DEBIAN12-PYTHON311-3325304","SNYK-DEBIAN12-PYTHON311-3325304","SNYK-DEBIAN12-PYTHON311-5853785","SNYK-DEBIAN12-PYTHON311-5853785"],"vulns":["SNYK-DEBIAN12-GNUTLS28-6159418","SNYK-DEBIAN12-PYTHON311-5853785","SNYK-DEBIAN12-PYTHON311-3325304"],"patch":[],"isBreakingChange":false,"remediationStrategy":"vuln"}'