chore(deps): update alpine docker tag to v3.21

This MR contains the following updates:

Package	Type	Update	Change
alpine	image	minor	3.19 -> 3.21

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.gitlab-ci.yml

@@ -18,7 +18,7 @@ workflow:
     - if: $CI_COMMIT_BRANCH
 
 lint-jinja:
-  image: alpine:3.19
+  image: alpine:3.21
   stage: lint
   before_script:
     - apk add --no-cache gcc musl-dev python3-dev make poetry py3-pip