Use full debian for CI

The containers are bigger, but it has all the required dependencies.
It's also what's run in production anyway.

.gitlab-ci.yml

@@ -22,7 +22,7 @@ static:
     expire_in: 30 mins
 
 pip:
-  image: python:3.10-slim
+  image: python:3.10
   stage: build
   variables:
     PIP_CACHE_DIR: $CI_PROJECT_DIR/.pip-cache
@@ -51,7 +51,7 @@ container:
     - docker build -t website .
 
 .python_test_template: &python_test_template
-  image: python:3.10-slim
+  image: python:3.10
   stage: test
   dependencies:
     - pip