.gitlab-ci.yml: use asan from fedora25 instead of centos7

The former provides a much newer version. Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

.gitlab-ci.yml: use asan from fedora25 instead of centos7
81492944 · Nikos Mavrogiannopoulos · Niels Möller · 27fe1a9e · 81492944
Commit 81492944 authored 8 years ago by Nikos Mavrogiannopoulos Committed by Niels Möller 8 years ago
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -45,6 +45,7 @@ Build and Check with ubsan:
  except:
  - tags
 Build and Check with asan:
+  image: fedora:25
  script:
  - yum install -y gmp-devel
  - ./.bootstrap &&