build(deps): bump alpine from 3.20.3 to 3.21.0

Bumps alpine from 3.20.3 to 3.21.0.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Dockerfile

@@ -51,7 +51,7 @@ RUN go install cuelang.org/go/cmd/cue@latest
 WORKDIR /examples
 
 ## RELEASE ##
-FROM alpine:3.20.3
+FROM alpine:3.21.0
 
 # Install git for protocols that depend on it when using conftest pull
 RUN apk add --no-cache git