AETHER-1027 Remove deleted edge from Prometheus metrics

Change-Id: Ia870e9c9835b1bbb7d23839134173fff360811c4
diff --git a/edge-monitoring/Makefile b/edge-monitoring/Makefile
index 0fc83de..f199fa4 100644
--- a/edge-monitoring/Makefile
+++ b/edge-monitoring/Makefile
@@ -57,8 +57,8 @@
 docker-push:
 	docker push ${ADAPTER_IMAGENAME}
 
-venv: ${VENVDIR}
-	virtualenv --python=python3.7 ${VENVDIR};\
+${VENVDIR}:
+	virtualenv --python=python3 ${VENVDIR};\
         source ./${VENVDIR}/bin/activate ; set -u ;\
         pip install -r requirements.txt