[babl] ci: use archlinux:base-20210214.0.15477 as base for building

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 3c3d749aa7d88ce3916c2ccf9aeb6036b7f526a2
Author: Øyvind Kolås <pippin gimp org>
Date:   Thu Feb 25 21:27:26 2021 +0100

    ci: use archlinux:base-20210214.0.15477 as base for building
    
    This gives us an arch base from before the glibc version that enforces
    a newer glibc package that has a hard dependency on a newer linux
    kernel.

 .gitlab-ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 89e1e3b00..10bbb712f 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -4,7 +4,7 @@ cache:
 
 .build:
   stage: build
-  image: archlinux:latest
+  image: archlinux:base-20210214.0.15477
   variables:
     PACMAN_CACHE: $CI_PROJECT_DIR/_pacman_cache
   artifacts: