fix: Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-ALPINE320-OPENSSL-8235201
- https://snyk.io/vuln/SNYK-ALPINE320-OPENSSL-8235201

Dockerfile

@@ -1,5 +1,5 @@
 # Use a clean tiny image to store artifacts in
-FROM alpine:3.20.3
+FROM alpine:3.21.0
 
 # Labels for http://label-schema.org/rc1/#build-time-labels
 # And for https://github.com/opencontainers/image-spec/blob/master/annotations.md