[enh] ci: coverage is directly defined by .gitlab-ci

.gitlab-ci.yml

@@ -81,7 +81,7 @@ test:
     - bash .gitlab/test/check_indexes.sh /tmp/duniter_ci_dump/
     # Code coverage display in GitLab
     - sed -n 23p coverage/index.html | grep -Po "\d+.\d+" | sed -e "s/\(.*\)/<coverage>\1%<\/coverage>/"
-
+  coverage: '/<coverage>(\d+.\d+\%)<\/coverage>/'
 .build_releases: &build_releases
   stage: package
   allow_failure: false