Fix black, flake8 and cover issues

Change-Id: I6baef962d0e272c415d9d19436ac4c6c08fc3d92
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 21f6ba6..268bdd8 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -15,18 +15,18 @@
 # limitations under the License.
 #######################################################################################
 aiokafka==0.7.2
-    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=master
+    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v12.0
 dataclasses==0.6
-    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=master
+    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v12.0
 kafka-python==2.0.2
     # via
-    #   -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=master
+    #   -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v12.0
     #   aiokafka
-osm-common @ git+https://osm.etsi.org/gerrit/osm/common.git@master
+osm-common @ git+https://osm.etsi.org/gerrit/osm/common.git@v12.0
     # 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=master
+    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v12.0
 pymongo==3.12.3
-    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=master
+    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v12.0
 pyyaml==5.4.1
-    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=master
+    # via -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v12.0