ci: switch to --password-stdin for secure docker registry login

.gitlab-ci.yml

@@ -100,7 +100,7 @@ docker-build:
   services:
     - docker:24.0.5-dind
   before_script:
-    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" "$CI_REGISTRY"
+    - echo "$CI_REGISTRY_PASSWORD" | docker login $CI_REGISTRY -u $CI_REGISTRY_USER --password-stdin
   script:
     - docker build -t "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG" -t "$CI_REGISTRY_IMAGE:latest" .
     - docker push "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG"