Fix module name in pytest --cov argument

This MR fixes the failing CI by manually setting the COVERAGE_TARGET variable for the pytest jobs; the default from the template no longer works because we renamed the repo.

.gitlab-ci.yml

@@ -153,6 +153,8 @@ deb:bullseye:
   needs:
     - tarball
   variables:
+    # target for coverage
+    COVERAGE_TARGET: "gwdatafind"
     # don't need the git repo
     GIT_STRATEGY: none
     # configure pytest