Update requirements-dev.in to follow branch v12.0 instead of master

Change-Id: I3d6cbbe92ad5abc5db95486d1bd0c22f5e469bdc
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/requirements-dev.in b/requirements-dev.in
index 33a3ab6..15f6462 100644
--- a/requirements-dev.in
+++ b/requirements-dev.in
@@ -10,8 +10,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-git+https://osm.etsi.org/gerrit/osm/common.git@master#egg=osm-common
--r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=master
+git+https://osm.etsi.org/gerrit/osm/common.git@v12.0#egg=osm-common
+-r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v12.0
 
-git+https://osm.etsi.org/gerrit/osm/IM.git@master#egg=osm-im
--r https://osm.etsi.org/gitweb/?p=osm/IM.git;a=blob_plain;f=requirements.txt;hb=master
+git+https://osm.etsi.org/gerrit/osm/IM.git@v12.0#egg=osm-im
+-r https://osm.etsi.org/gitweb/?p=osm/IM.git;a=blob_plain;f=requirements.txt;hb=v12.0