added diffutils package to tumbleweed

dockerfiles/tumbleweed.docker

@@ -26,6 +26,7 @@ RUN zypper refresh && \
     zypper install -y vim && \
     zypper install -y python3-pytest && \
     zypper install -y perl-JSON && \
+    zypper install -y diffutils && \
     useradd -u 30996 msk_jenkins && \
     ln -sfn /usr/lib64/libzmq.so.5 /usr/lib64/libzmq.so.3