Sync lua coverage with .drone.yml

.circleci/config.yml

@@ -113,6 +113,10 @@ jobs:
       - run: cd ../build
       # see coverage notice in "build" stage
       - run: set +e; RSPAMD_INSTALLROOT=../install sudo -E bash -c "umask 0000; robot -x xunit.xml --exclude isbroken ../project/test/functional/cases"; echo "export RETURN_CODE=$?" >> $BASH_ENV
+      # luacov-coveralls reads luacov.stats.out generated by functional tests
+      # (see collect_lua_coverage() in test/functional/lib/rspamd.py)
+      # and writes json report for coveralls.io
+      - run: luacov-coveralls -o lua_coverage_report.json --dryrun
 
       - *capture_coverage_data