gnocchi: add python3-rados to gnocchi-base source image

The binary images include python3-rados as a dependency, but source
images do not. This change fixes that.

Change-Id: I2c8cdfcd25856ecdcfd9f302965187b3b62376ad
Closes-Bug: #1927756

Author: markgoddard

docker/gnocchi/gnocchi-base/Dockerfile.j2

@@ -49,6 +49,7 @@ RUN {{ macros.install_pip(gnocchi_base_pip_packages | customizable("pip_packages
 
        {% set gnocchi_base_packages = [
             'librados2-devel',
+            'python3-rados',
         ] %}
 
 {{ macros.install_packages(gnocchi_base_packages | customizable("packages")) }}
@@ -57,6 +58,7 @@ RUN mkdir -p /var/www/cgi-bin/gnocchi
 
        {% set gnocchi_base_packages = [
             'librados-dev',
+            'python3-rados',
         ] %}
 
 {{ macros.install_packages(gnocchi_base_packages | customizable("packages")) }}