PHOENIX-6675 create-release script broken by upgrade to Yetus 0.13
diff --git a/dev/create-release/phoenix-rm/Dockerfile b/dev/create-release/phoenix-rm/Dockerfile
index be91e9a..9aa97aa 100644
--- a/dev/create-release/phoenix-rm/Dockerfile
+++ b/dev/create-release/phoenix-rm/Dockerfile
@@ -38,12 +38,15 @@
     maven='3.6.0-*' \
     openjdk-8-jdk='8*' \
     python-pip='9.0.1-*' \
+    python3-pip='9.0.1-*' \
     subversion='1.9.7-*' \
     wget='1.19.4-*' \
   && apt-get clean \
   && rm -rf /var/lib/apt/lists/* \
   && update-alternatives --set java /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java \
   && pip install \
+    python-dateutil==2.8.1 \
+  && pip3 install \
     python-dateutil==2.8.1
 # Install Apache Yetus
 ENV YETUS_VERSION 0.13.0