BugFix: clean rule in Makefile

scripts/Makefile

 	@ls testresults | xargs -i rm -f "testresults/{}"
 	@echo -e "\e[1m  * Collected coverage information\e[0m"
 	@$(COV3_CMD) erase
-	@rm -r venv3
 
 cleanall: clean
 	@echo "\e[1m  * Virtualenv\e[0m"