Bump node from 18-alpine3.21 to 24-alpine3.21 in /cmd/hub

Bumps node from 18-alpine3.21 to 24-alpine3.21.

---
updated-dependencies:
- dependency-name: node
  dependency-version: 24-alpine3.21
  dependency-type: direct:production
...

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

Author: dependabot[bot]

cmd/hub/Dockerfile

@@ -8,7 +8,7 @@ WORKDIR /go/src/github.com/artifacthub/hub/cmd/hub
 RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o /hub .
 
 # Build frontend
-FROM node:18-alpine3.21 AS frontend-builder
+FROM node:24-alpine3.21 AS frontend-builder
 RUN apk --no-cache add jq
 WORKDIR /web
 COPY web .
@@ -17,7 +17,7 @@ RUN yarn install
 RUN yarn build
 
 # Build widget
-FROM node:18-alpine3.21 AS widget-builder
+FROM node:24-alpine3.21 AS widget-builder
 WORKDIR /widget
 COPY widget .
 ENV NODE_OPTIONS=--max_old_space_size=4096