build(deps): bump alpine

Bumps alpine from 3.20 to 3.21.

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

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

network/tools/network-policy-enforcement-latency/pod-creation-reachability-latency/Dockerfile

@@ -8,7 +8,7 @@ WORKDIR /go/src/$gopkg/pod-creation-reachability-latency
 RUN go build -o /pod-creation-reachability-latency
 
 # Runtime image
-FROM alpine:3.20
+FROM alpine:3.21
 # Need to install curl to send requests to pods
 RUN apk --no-cache add curl