[fractal] change CI rust-fmt checks to stable rust

[Daniel Garcia Moreno <danigm src gnome org>]

commit ac42237675bfbd855872068b85f7860669855f33
Author: mairandomness <mairakodama gmail com>
Date:   Sat Feb 2 14:32:22 2019 -0500

    change CI rust-fmt checks to stable rust

 .gitlab-ci.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 21c947cc..d949c0b2 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -21,12 +21,12 @@ variables:
           - target_test/
 
 check:
-    image: "registry.gitlab.com/alatiera/rustfmt-oci-image/rustfmt:nightly"
+    image: "registry.gitlab.com/alatiera/rustfmt-oci-image/rustfmt:stable"
     stage: "check"
     script:
         - rustc -Vv && cargo -Vv
-        - cargo +nightly --version
-        - cargo +nightly fmt --all -- --check
+        - cargo --version
+        - cargo fmt --all -- --check
 
 flatpak:
     image: "registry.gitlab.gnome.org/gnome/gnome-runtime-images/rust_bundle:master"