[gtk-doc] ci: bump meson deps in dockerfile

[Stefan Sauer <stefkost src gnome org>]

commit 0cfbbc808a19cf333f7b8b642971f53df261cdb4
Author: Stefan Sauer <ensonic users sf net>
Date:   Sun Jul 28 11:55:03 2019 +0200

    ci: bump meson deps in dockerfile

 .gitlab-ci.yml               | 2 +-
 .gitlab-ci/README.md         | 4 ++--
 .gitlab-ci/debian.Dockerfile | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index b9d5d89..ee5dfbf 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: registry.gitlab.gnome.org/gnome/gtk-doc/debian:v1
+image: registry.gitlab.gnome.org/gnome/gtk-doc/debian:v2
 
 stages:
   - build
diff --git a/.gitlab-ci/README.md b/.gitlab-ci/README.md
index dc6c821..5cb6205 100644
--- a/.gitlab-ci/README.md
+++ b/.gitlab-ci/README.md
@@ -6,9 +6,9 @@ GitLab CI jobs run in a Docker image, defined here. To update that image
 (perhaps to install some more packages):
 
 1. Edit `.gitlab-ci/Dockerfile` with the changes you want
-1. Run `.gitlab-ci/run-docker.sh build --base=debian --base-version=1` to build
+1. Run `.gitlab-ci/run-docker.sh build --base=debian --base-version=2` to build
    the new image (bump the version as needed)
-1. Run `.gitlab-ci/run-docker.sh push  --base=debian --base-version=1` to upload
+1. Run `.gitlab-ci/run-docker.sh push  --base=debian --base-version=2` to upload
    the new image to the GNOME GitLab Docker registry
     * If this is the first time you're doing this, you'll need to log into the
       registry
diff --git a/.gitlab-ci/debian.Dockerfile b/.gitlab-ci/debian.Dockerfile
index 275fafa..5015385 100644
--- a/.gitlab-ci/debian.Dockerfile
+++ b/.gitlab-ci/debian.Dockerfile
@@ -47,7 +47,7 @@ RUN locale-gen de_DE.UTF-8 \
 
 ENV LANG=C.UTF-8 LANGUAGE=C.UTF-8 LC_ALL=C.UTF-8
 
-RUN pip3 install meson==0.48.0 anytree
+RUN pip3 install meson==0.50.0 anytree
 ARG HOST_USER_ID=5555
 ENV HOST_USER_ID ${HOST_USER_ID}
 RUN useradd -u $HOST_USER_ID -ms /bin/bash user