Update Docker build/CI

.dockerignore

+*
+!/requirements.txt
\ No newline at end of file

.gitlab-ci.yml

 stages:
-  - docker
   - build
+  - process
   - deploy
 
 Build Docker image:
-  stage: docker
-  only:
-    changes:
-      - Dockerfile.ci
-      - requirements.txt
-    refs:
-      - master
-    variables:
-      # Do not build Docker image from scheduled jobs.
-      # Cf https://gitlab.com/gitlab-org/gitlab/issues/27318#note_215688359
-      - $CI_PIPELINE_SOURCE == "push"
+  stage: build
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "push"
+      changes:
+        - Dockerfile
+        - requirements.txt
+      when: always
   image:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
   script:
     - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
-    - /kaniko/executor --context $CI_PROJECT_DIR --dockerfile $CI_PROJECT_DIR/Dockerfile.ci --destination $CI_REGISTRY_IMAGE:$CI_COMMIT_TAG
+    - /kaniko/executor --cache --context $CI_PROJECT_DIR --dockerfile $CI_PROJECT_DIR/Dockerfile --destination $CI_REGISTRY_IMAGE:latest
 
 Download and generate data:
-  stage: build
+  stage: process
   except:
     - pushes
   image: $CI_REGISTRY_IMAGE:latest

Dockerfile.ci → Dockerfile

-FROM python:3.7-buster
+FROM python:3.9-slim-buster
 
 LABEL maintainer="contact@jailbreak.paris"