Changing common branch in requirements-dev.txt

Change-Id: Ib9d195ace43726cbec34fe86aacf6641189ef62b
Signed-off-by: Gulsum Atici <gulsum.atici@canonical.com>
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 21f6ba6..ce8c3ce 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=master
     #   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