Bump alpine from 3.20.3 to 3.21.2 (#618)

Bumps alpine from 3.20.3 to 3.21.2.

---
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

@@ -6,7 +6,7 @@ WORKDIR /build
 ADD . /build
 RUN make BUILD_VERSION=${VERSION}
 
-FROM alpine:3.20.3@sha256:beefdbd8a1da6d2915566fde36db9db0b524eb737fc57cd1367effd16dc0d06d AS runner
+FROM alpine:3.21.2@sha256:56fa17d2a7e7f168a043a2712e63aed1f8543aeafdcee47c58dcffe38ed51099 AS runner
 LABEL org.opencontainers.image.source="https://github.com/DataDog/stratus-red-team/"
 COPY --from=builder /build/bin/stratus /stratus
 RUN apk add --update git # git is needed for Terraform to download external modules at runtime