Use "." instead of "source" in Makefile

Makefile

@@ -6,14 +6,16 @@ PY_VER=python3.11
 PYTHON=./$(VENV)/bin/$(PY_VER)
 PIP_INSTALL=$(PYTHON) -m pip install
 SPACY_MODEL=$(PYTHON) -m spacy download en_core_web_md
+ACTIVATE=. $(VENV)/bin/activate
 
 test:
+	$(ACTIVATE)
 	export MOCK_DATA=1
 	$(PYTHON) -m unittest discover
 	export MOCK_DATA=0
 
 install: venv
-	source $(VENV)/bin/activate
+	$(ACTIVATE)
 	$(PIP_INSTALL) -U pip setuptools wheel
 	$(PIP_INSTALL) git+https://github.com/rafelafrance/common_utils.git@main#egg=common_utils
 	$(PIP_INSTALL) git+https://github.com/rafelafrance/spell-well.git@main#egg=spell-well
@@ -22,7 +24,7 @@ install: venv
 	$(SPACY_MODEL)
 
 dev: venv
-	source $(VENV)/bin/activate
+	$(ACTIVATE)
 	$(PIP_INSTALL) -U pip setuptools wheel
 	$(PIP_INSTALL) -e ../../misc/common_utils
 	$(PIP_INSTALL) -e ../../misc/spell-well