[librsvg-oci-images] Add rustc 1.28.0 and update 1.27 tag to 1.27.2

[Jordan Petridis <jpetridis src gnome org>]

commit d9125c3f944b040d9dc63d41c02231b635e3d6a1
Author: Jordan Petridis <jordanpetridis protonmail com>
Date:   Fri Aug 3 04:28:20 2018 +0000

    Add rustc 1.28.0 and update 1.27 tag to 1.27.2

 .gitlab-ci.yml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 35e956d..6f2d204 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -117,9 +117,15 @@ ubuntu_i386:18.04:
 
     <<: *distro_build
 
+rustc:1.28:
+    variables:
+      RUSTC_VERSION: "1.28.0"
+      TAG_VERSION: "1.28"
+    <<: *rustc
+
 rustc:1.27:
     variables:
-      RUSTC_VERSION: "1.27.0"
+      RUSTC_VERSION: "1.27.2"
       TAG_VERSION: "1.27"
     <<: *rustc