Fix python3 compatibility for barbican

Barbican refers to python3 but uwsgi refers to python2. This change
fixes this issue.

Change-Id: I508bb082a319955b3e008235e158eaa07a1e8a74
Closes-Bug: #1849128
(cherry picked from commit 823e45a)

Author: dincercelik

docker/barbican/barbican-api/Dockerfile.j2

@@ -35,7 +35,7 @@ RUN sed -i -r 's,^(Listen 80),#\1,' /etc/httpd/conf/httpd.conf \
                 'apache2',
                 'barbican-api',
                 'libapache2-mod-wsgi-py3',
-                'uwsgi-plugin-python'
+                'uwsgi-plugin-python3'
         ] %}
 
 {{ macros.install_packages(barbican_api_packages | customizable("packages")) }}

docker/barbican/barbican-base/Dockerfile.j2

@@ -25,7 +25,7 @@ LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build
         {% endif %}
 
     {% elif base_package_type == 'deb' %}
-        {% set barbican_base_packages = ['uwsgi-plugin-python'] %}
+        {% set barbican_base_packages = ['uwsgi-plugin-python3'] %}
     {% endif %}
 
 {{ macros.install_packages(barbican_base_packages | customizable("packages")) }}