chore: upgrade Alpine Linux from 3.21 to 3.22

Upgrades all Alpine base images from 3.21 to 3.22 to address
end-of-life nginx version.

- Alpine 3.21 ships nginx 1.26.3 which reached EOL on April 23, 2025
- Alpine 3.22 ships nginx 1.28.0 which is currently supported
- Ensures the project receives security updates for nginx

Updated images:
- alpine:3.21 -> alpine:3.22 (uploader and final stages)
- node:22-alpine3.21 -> node:22-alpine3.22 (build stage)

Author: singh-akshay

docker/Dockerfile

@@ -1,5 +1,5 @@
 # syntax = docker/dockerfile:1.3
-FROM            alpine:3.21 as uploader
+FROM            alpine:3.22 as uploader
 USER            root
 WORKDIR         /tmp
 RUN             apk -U add gpg gpg-agent curl
@@ -38,7 +38,7 @@ RUN             gpg --verify linux/codecov.SHA256SUM.sig linux/codecov.SHA256SUM
 
 COPY            docker/index.html /tmp/uploader
 
-FROM node:22-alpine3.21 as build
+FROM node:22-alpine3.22 as build
 ARG REACT_APP_ENV_ARG
 ARG REACT_APP_CODECOV_VERSION
 ENV REACT_APP_ENV=$REACT_APP_ENV_ARG
@@ -53,7 +53,7 @@ RUN yarn install
 RUN yarn build && rm -f build/mockServiceWorker.js
 
 
-FROM alpine:3.21
+FROM alpine:3.22
 ARG REACT_APP_CODECOV_VERSION
 ARG ENVIRONMENT
 ARG COMMIT_SHA