[rhythmbox/wip/sam/meson] ci: Use Ubuntu 20.04

[Sam Thursfield <sthursfield src gnome org>]

commit b4a495586dab923160d6e3eb3a4c8fc217fb6962
Author: Sam Thursfield <sam afuera me uk>
Date:   Thu Oct 29 12:30:36 2020 +0100

    ci: Use Ubuntu 20.04
    
    On bionic I see this error:
    
        ../lib/libmediaplayerid/meson.build:38:0: ERROR: Static libraries can only be introspected with 
GObject-Introspection >=1.58.1

 .gitlab-ci.yml | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index bcbc4963f..72e643e74 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: ubuntu:bionic
+image: ubuntu:focal
 
 stages:
   - test
@@ -12,10 +12,9 @@ before_script:
                        libsoup2.4-dev libgudev-1.0-dev libmtp-dev libnotify-dev
                        libbrasero-media3-dev
                        libsecret-1-dev libpeas-dev yelp-tools x11proto-core-dev
-                       liblircclient-dev python3-dev python-gi-dev python3-pip
+                       liblircclient-dev python3-dev python-gi-dev
                        libdmapsharing-3.0-dev libjson-glib-dev libgrilo-0.3-dev
-                       libxml2-dev libtdb-dev ninja-build
-  - pip3 install meson
+                       libxml2-dev libtdb-dev meson ninja-build
 
 test:
   stage: test