.gitlab-ci.yml: Use stretch Debian image instead of unstable

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 5fcd54fd94475f91ce7e140be013d279921bf43e..0b1e8b5d9f7043a206b960f138bb8a8a94a9f3ef 100644 (file)
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -24,7 +24,7 @@
 # Maintainer: tzz@lifelogs.com
 # URL: https://gitlab.com/emacs-ci/emacs
 
-image: debian:unstable
+image: debian:stretch
 
 before_script:
   - apt update -qq