update requirements to use python3

installer/lib/requirements-debian-stretch.apt

@@ -1,71 +1,53 @@
 apache2
+coreutils
+curl
+ecasound
+flac
 git
+gstreamer1.0-plugins-ugly
+icecast2
+lame
+libao-ocaml
 libapache2-mod-php7.0
-php7.0
-php7.0-dev
-php7.0-bcmath
-php7.0-mbstring
-php-pear
-php7.0-gd
-php-amqplib
-
-lsb-release
-
-zip
-unzip
-
-rabbitmq-server
-
-postgresql
-postgresql-client
-php7.0-pgsql
-
-python
-python-virtualenv
-python-pip
-
+libcamomile-ocaml-data
+libfaad2
+libmad-ocaml
+libopus0
+libportaudio2
+libpulse0
+libsamplerate0
 libsoundtouch-ocaml
 libtaglib-ocaml
-libao-ocaml
-libmad-ocaml
-ecasound
-libportaudio2
-libsamplerate0
 libvo-aacenc0
-
-python-rgain
-python-gst-1.0
-gstreamer1.0-plugins-ugly
-python-pika
-
-patch
-
-icecast2
-
-curl
-php7.0-curl
-mpg123
-
-libcamomile-ocaml-data
-libpulse0
-vorbis-tools
+liquidsoap
+lsb-release
 lsb-release
 lsof
-vorbisgain
-flac
-vorbis-tools
-pwgen
-libfaad2
+mpg123
+patch
+php7.0
+php7.0-bcmath
+php7.0-curl
+php7.0-dev
+php7.0-gd
+php7.0-mbstring
+php7.0-pgsql
+php-amqplib
 php-apcu
-
-lame
-
-coreutils
-
-liquidsoap
-
-libopus0
-
+php-pear
+postgresql
+postgresql-client
+pwgen
+python3
+python3-gst-1.0
+python3-pika
+python3-pip
+python3-virtualenv
+rabbitmq-server
 systemd-sysv
-
+unzip
+vorbisgain
+vorbis-tools
+vorbis-tools
 xmlstarlet
+zip