Bump alpine from 3.17 to 3.18

Bumps alpine from 3.17 to 3.18.

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

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

Dockerfile.backend

@@ -28,7 +28,7 @@ RUN --mount=type=cache,target=/go/pkg/mod \
      -X 'github.com/openclarity/vmclarity/backend/pkg/version.CommitHash=${COMMIT_HASH}' \
      -X 'github.com/openclarity/vmclarity/backend/pkg/version.BuildTimestamp=${BUILD_TIMESTAMP}'" -o backend ./cmd/backend/main.go
 
-FROM alpine:3.17
+FROM alpine:3.18
 
 WORKDIR /app