Update requirements-dev to point to v18.0 branch

Change-Id: I6db321b5aadb4cafb8a192133f2ac9b919a8e269
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/requirements-dev.in b/requirements-dev.in
index c113bba..e293ccb 100644
--- a/requirements-dev.in
+++ b/requirements-dev.in
@@ -13,5 +13,5 @@
 # See the 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@v18.0#egg=osm-common
+-r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=v18.0