Fix typo in clean-tests target
This change fixes the clean-tests Makefile target. It was missing the
's'.
@@ -481,4 +481,4 @@ clean-temp:
-rm -f integration-report.xml report.xml
.PHONY: clean-tests
-clean-test: clean-temp clean-fixtures
\ No newline at end of file
+clean-tests: clean-temp clean-fixtures
\ No newline at end of file
