[simple-scan] Use symbolic names for Docker containers. Fix Fedora package names

[Robert Ancell <rancell src gnome org>]

commit ba2035eb62cba1a047f5e25cca7bdbc7d6e6b7c7
Author: Robert Ancell <robert ancell canonical com>
Date:   Thu Dec 7 10:38:38 2017 +1300

    Use symbolic names for Docker containers. Fix Fedora package names

 .gitlab-ci.yml | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 6d30faa..4c9897e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -2,7 +2,7 @@ stages:
  - build
 
 build-ubuntu-lts:
-  image: ubuntu:16.04
+  image: ubuntu:latest
   stage: build
   before_script:
     - apt-get update
@@ -12,7 +12,7 @@ build-ubuntu-lts:
     - ninja -C _build install
 
 build-ubuntu-latest:
-  image: ubuntu:17.10
+  image: ubuntu:rolling
   stage: build
   before_script:
     - apt-get update
@@ -22,10 +22,10 @@ build-ubuntu-latest:
     - ninja -C _build install
 
 build-fedora:
-  image: fedora:27
+  image: fedora:latest
   stage: build
   before_script:
-    - dnf install -y meson valac gettext itstool gtk3-devel libgusb-devel colord-devel 
PackageKit-glib2-devel libwebp-devel sane-backends-devel
+    - dnf install -y meson vala gettext itstool gtk3-devel libgusb-devel colord-devel PackageKit-glib-devel 
libwebp-devel sane-backends-devel
   script:
     - meson _build
     - ninja -C _build install