Update CI syntax to latest standard and conventions

Remove second unnecessary login

.gitlab-ci.yml

 test_build_image:
-  image: docker:git
+  image: docker:latest
   tags:
-  - docker
+    - docker
   services:
-  - docker:dind
+    - docker:dind
   script:
     - docker build 3.9
     - docker build 3.10
@@ -14,42 +14,41 @@ test_build_image:
     - tags
 
 .build_image:
-  image: docker:git
+  image: docker:latest
   tags:
-  - docker
+    - docker
   services:
-  - docker:dind
+    - docker:dind
   script:
-    - docker login -u "gitlab-ci-token" -p "$CI_JOB_TOKEN" $CI_REGISTRY
+    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
     - docker build --pull -t "$CI_REGISTRY_IMAGE/$PYTHON_VERSION:$CI_COMMIT_TAG" $PYTHON_VERSION
-    - docker login -u "gitlab-ci-token" -p "$CI_JOB_TOKEN" $CI_REGISTRY
     - docker push "$CI_REGISTRY_IMAGE/$PYTHON_VERSION:$CI_COMMIT_TAG"
     - docker tag "$CI_REGISTRY_IMAGE/$PYTHON_VERSION:$CI_COMMIT_TAG" "$CI_REGISTRY_IMAGE/$PYTHON_VERSION:latest"
     - docker push "$CI_REGISTRY_IMAGE/$PYTHON_VERSION:latest"
-  only:
-    - tags
+  rules:
+    - if: $CI_COMMIT_TAG
 
-build_3_9:
+build:3.9:
   extends: .build_image
   variables:
     PYTHON_VERSION: "3.9"
 
-build_3_10:
+build:3.10:
   extends: .build_image
   variables:
     PYTHON_VERSION: "3.10"
 
-build_3_11:
+build:3.11:
   extends: .build_image
   variables:
     PYTHON_VERSION: "3.11"
 
-build_3_12:
+build:3.12:
   extends: .build_image
   variables:
     PYTHON_VERSION: "3.12"
 
-build_3_13:
+build:3.13:
   extends: .build_image
   variables:
     PYTHON_VERSION: "3.13"