Fix black and cover errors

Change-Id: Ic6b5d4babf5d7da3f1e78b0ed1abd5110bc9a904
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 3d56590..1c89a18 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -22,7 +22,7 @@
     # via
     #   -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v13.0
     #   aiokafka
-osm-common @ git+https://osm.etsi.org/gerrit/osm/common.git@master
+osm-common @ git+https://osm.etsi.org/gerrit/osm/common.git@v13.0
     # via -r requirements-dev.in
 pycrypto==2.6.1
     # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v13.0