Update Dockerfiles to upgrade pip before installing osm-common to avoid unknown package naming

Change-Id: I200063211508d1bf08532f7c3af76768e635bf6c
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/docker/NBI/Dockerfile b/docker/NBI/Dockerfile
index f7d823d..dce5590 100644
--- a/docker/NBI/Dockerfile
+++ b/docker/NBI/Dockerfile
@@ -41,13 +41,14 @@
     && rm -rf /var/lib/apt/lists/*
 
 ARG COMMON_GERRIT_REFSPEC=master
+RUN pip3 install -U pip build
 RUN git clone --filter=blob:none --tags https://osm.etsi.org/gerrit/osm/common.git /tmp/osm-common && \
     cd /tmp/osm-common && \
     git fetch origin ${COMMON_GERRIT_REFSPEC} && \
     git checkout FETCH_HEAD && \
     cd - && \
-    pip install --no-cache-dir -r /tmp/osm-common/requirements.txt && \
-    pip install /tmp/osm-common
+    pip3 install --no-cache-dir -r /tmp/osm-common/requirements.txt && \
+    pip3 install /tmp/osm-common
 
 ARG PYTHON3_OSM_IM_URL
 ARG PYTHON3_OSM_NBI_URL