Gitlab CI: install arraycontext

Author: inducer

.gitlab-ci.yml

@@ -52,6 +52,7 @@ Mypy:
   script: |
     curl -L -O https://tiker.net/ci-support-v0
     . ./ci-support-v0
+    export EXTRA_INSTALL="git+https://github.com/inducer/arraycontext"
     build_py_project_in_venv
     python -m pip install mypy mpi4py
     ./run-mypy.sh