[librsvg: 2/3] Use the cargo cache for the fmt stage in CI

[Marge Bot <marge-bot src gnome org>]

commit 17ae0a014f2b3ddff21e68fc8d4effd27d6130cb
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Jul 27 19:56:19 2021 -0500

    Use the cargo cache for the fmt stage in CI
    
    Let's see if this fixes this:
    
    $ sudo -E cargo fmt --all -- --check
    Error during execution of `cargo metadata`:  Downloading crates ...
      Downloaded adler32 v1.2.0
      Downloaded tinyvec_macros v0.1.0
      Downloaded stable_deref_trait v1.2.0
      ... which often fails later
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/573>

 .gitlab-ci.yml | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 12bd35a8..0ee9f632 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -66,6 +66,7 @@ check:
 
 fmt:
   stage: lint
+  extends: '.cache'
   needs:
     - job: check
   script: