Bump alpine from 3.20.3 to 3.21.0 (#45)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.20.3 as builder
+FROM alpine:3.21.0 as builder
 
 WORKDIR /go/src/github.com/systemli/dereferrer