build: Cleanup python2 from suse build and uplift opensuse version

 - default to opensuse-leap 15.4, no python2 support in this version
 - deprecate version openSUSE 15.0, openSUSE 15.3 still supported

Type: make

Signed-off-by: Laszlo Kiraly <laszlo.kiraly@est.tech>
Change-Id: Ic7178ff5238e2669bc45166c1f13d3f077f6069b
Signed-off-by: Laszlo Kiraly <laszlo.kiraly@est.tech>
diff --git a/extras/rpm/opensuse/Dockerfile b/extras/rpm/opensuse/Dockerfile
index 47ca271..34a39ea 100644
--- a/extras/rpm/opensuse/Dockerfile
+++ b/extras/rpm/opensuse/Dockerfile
@@ -1,11 +1,12 @@
 # Run from top of vpp repo with command:
 # docker build -f extras/rpm/opensuse/Dockerfile .
 
-ARG SUSE_VERSION=15.3
+ARG SUSE_VERSION=15.4
 
 FROM opensuse/leap:${SUSE_VERSION} as vppbuild
 COPY . /vpp
 WORKDIR /vpp
+RUN zypper refresh
 RUN zypper install -y make sudo
 COPY . .
 RUN UNATTENDED=y make install-dep