Fix multiple issues

Both issues affect Train and earlier releases.

1. Fix monasca-grafana by pinning more Ruby gems

childprocess 3.0.0 and ffi 1.13.0 depend on Ruby 2.3.

2. Bump bifrost to 7.2.1

Bifrost had a fix to stop using the master branch of DIB which dropped
support for Python 2.

Change-Id: Ida7e20833360bbca69c6aafc4f5d7cb375bb106f
Closes-Bug: #1882070

docker/monasca/monasca-grafana/Dockerfile.j2

@@ -53,7 +53,8 @@ ARG monasca_grafana_url=https://github.com/monasca/grafana/archive/$monasca_graf
 # NOTE(yoctozepto): Update npm to 6.x version to avoid issues with metadata parsing.
 # NPM installs itself in /usr/local/bin (the default in Ubuntu) which is not in the PATH.
 # This is forced for all distros to avoid conflicts with native packages.
-RUN gem install rake:"~>12" fpm \
+# NOTE(mgoddard): childprocess 3.0.0 and ffi 1.13.0 depend on Ruby 2.3.
+RUN gem install rake:"~>12" ffi:"<1.13.0" childprocess:"<2.0.0" fpm \
     && curl -sSL -o /tmp/monasca-grafana.tgz ${monasca_grafana_url} \
     && mkdir -p ${monasca_grafana_build_path} \
     && tar --strip 1 -xvf /tmp/monasca-grafana.tgz -C ${monasca_grafana_build_path} \

kolla/common/config.py

@@ -323,7 +323,7 @@ SOURCES = {
     'bifrost-base': {
         'type': 'url',
         'location': ('$tarballs_base/bifrost/'
-                     'bifrost-7.2.0.tar.gz')},
+                     'bifrost-7.2.1.tar.gz')},
     'blazar-base': {
         'type': 'url',
         'location': ('$tarballs_base/blazar/'