makefile: add removal of .mypy_cache to make clean

Makefile

@@ -7,7 +7,7 @@ mypy: ## Run static type checker
 
 .PHONY: clean
 clean:  ## Clean the workspace of generated resources
-	@rm -rf build dist *.egg-info .coverage .eggs docs/_build .pytest_cache lib htmlcov .cache && \
+	@rm -rf .mypy_cache build dist *.egg-info .coverage .eggs docs/_build .pytest_cache lib htmlcov .cache && \
 		find . \( -name '*.py[co]' -o -name dropin.cache \) -delete && \
 		find . \( -name '*.bak' -o -name dropin.cache \) -delete && \
 		find . \( -name '*.tgz' -o -name dropin.cache \) -delete && \