Bump alpine from 28bd5fe to 294b683

[dependabot]

Bumps alpine from 28bd5fe to 294b683.

[Farjaad]

@dependabot rebase

[Farjaad]

Dependabot review: safe to merge ✅

This bumps the runtime base image digest from Alpine 3.24.1 to 3.24.2, a one-line change in the root Dockerfile. The new digest matches the official alpine:3.24.2 / latest image on Docker Hub. The golang:alpine build stage is unchanged.

• Release notes: 3.24.2 is a security patch release that fixes high- and medium-severity OpenSSL vulnerabilities (announcement). It has no breaking changes.
• Impact on the runner: Minimal. The binary is built statically (CGO_ENABLED=0 in src/.goreleaser.yml), so it doesn't use the image's musl or OpenSSL. CA certificates are copied from the build stage. The new image includes both architectures we publish, linux/amd64 and linux/arm64.
• CI: test passed. CodeQL was skipped, which is expected for a Dockerfile-only change.

Note: no PR check builds the Docker image; only the release workflow does. It's worth confirming that opslevel-runner version runs on the published image after the next release.