Remove references to "python-cddb"

The use of this Python package was replaced in commit
542e071443 with another CDDB/FreeDB API
implemention, but it was still being installed for Travis CI builds and
for Docker containers.

Signed-off-by: Frederik “Freso” S. Olesen <freso.dk@gmail.com>

.travis.yml

@@ -10,7 +10,7 @@ install:
     # Dependencies
     - sudo apt-get -qq update
     - sudo pip install --upgrade -qq pip
-    - sudo apt-get -qq install cdparanoia cdrdao flac gir1.2-glib-2.0 libcdio-dev libiso9660-dev libsndfile1-dev python-cddb python-gi python-musicbrainzngs python-mutagen python-setuptools sox swig libcdio-utils
+    - sudo apt-get -qq install cdparanoia cdrdao flac gir1.2-glib-2.0 libcdio-dev libiso9660-dev libsndfile1-dev python-gi python-musicbrainzngs python-mutagen python-setuptools sox swig libcdio-utils
     - sudo pip install pycdio==0.21 requests setuptools_scm
 
     # Testing dependencies

Dockerfile

@@ -2,7 +2,7 @@ FROM debian:buster
 
 RUN apt-get update \
   && apt-get install -y cdrdao python-gobject-2 python-musicbrainzngs python-mutagen python-setuptools \
-  python-cddb python-requests libsndfile1-dev flac sox \
+  python-requests libsndfile1-dev flac sox \
   libiso9660-dev python-pip swig make pkgconf \
   eject locales \
   autoconf libtool curl \