CI: Parse Coverage percentage

This will effectively show coverage on MRs, and also in Analytics
diff --git a/.gitlab/ci_nightly.yml b/.gitlab/ci_nightly.yml
index a71d43b..633cb0a 100644
--- a/.gitlab/ci_nightly.yml
+++ b/.gitlab/ci_nightly.yml
@@ -80,6 +80,7 @@
       --html --html-details ../coverage-html/coverage.html
       --print-summary
       -r ../ .
+  coverage: '/lines:\s(\d+.\d+\%)/'
   artifacts:
     reports:
       coverage_report: