Merge branch 'mypy-from-debian' into 'master'

gitlab-ci: use mypy from Debian/bullseye to prevent random breakage

See merge request fdroid/fdroidserver!952

.gitlab-ci.yml

@@ -1,7 +1,7 @@
 
 variables:
   pip: pip3 --timeout 100 --retries 10
-# speed up git checkout phase
+  # speed up git checkout phase
   GIT_DEPTH: 1
 
 
@@ -202,9 +202,16 @@ lint_format_safety_bandit_checks:
 
 
 lint_mypy:
-  image: python:3.9-buster
+  image: debian:bullseye
+  <<: *apt-template
   script:
-    - pip install mypy
+    - sed -i '/pyjks/d' setup.py  # TODO get from backports once available
+    # use Debian packages to avoid building C/rust sources
+    - apt-get install
+          mypy
+          python3-cryptography
+          python3-pip
+          python3-wheel
     - pip install -e .[test]
     # exclude vendored file
     - mypy --exclude fdroidserver/apksigcopier.py
@@ -427,6 +434,7 @@ Build documentation:
     paths:
       - docs/build/html/
 
+
 pages:
   image: alpine:latest
   stage: deploy