Fix black issues and run tox properly in stage-test

Change-Id: Ie08f3029df03f97f1df1461a564c24ce024974fe
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/requirements.txt b/requirements.txt
index bcd2c46..eb66bc2 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -26,7 +26,7 @@
     # via aiohttp
 checksumdir==1.2.0
     # via -r requirements.in
-grpcio==1.49.1
+grpcio==1.50.0
     # via grpcio-tools
 grpcio-tools==1.48.1
     # via -r requirements.in