fix(deps): upgrade to alpine:3.21.6

[snyk-io]

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):

• Dockerfile

We recommend upgrading to alpine:3.21.6, as this image has only 8 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
	CVE-2025-26519 SNYK-ALPINE321-MUSL-8720634	614
	CVE-2025-26519 SNYK-ALPINE321-MUSL-8720634	614
	CVE-2025-69421 SNYK-ALPINE321-OPENSSL-15121241	614
	CVE-2025-69421 SNYK-ALPINE321-OPENSSL-15121241	614
	Always-Incorrect Control Flow Implementation SNYK-ALPINE321-MUSL-16008608	436

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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.

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[snyk-io]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues
✅	Licenses	0	0	0	0	0 issues
✅	Code Security	0	0	0	0	0 issues

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