[gtk/ci-gtk3-msys2-64bit] CI: switch MSYS2 jobs to 64bit

[Christoph Reiter <creiter src gnome org>]

commit 366374a3a0039f34f6ea1a46add3df27faf17fac
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Mon Jun 1 18:09:45 2020 +0200

    CI: switch MSYS2 jobs to 64bit
    
    g-i randomly fails, maybe its a 32bit toolchain issue, so try switching
    to 64bit which should be more tested/used nowadays.

 .gitlab-ci.yml | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 8df6eaab17..f2c9beed29 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -64,9 +64,9 @@ reference:
       - gdk3-docs.tar.xz
       - gtk3-docs.tar.xz
 
-msys2-mingw32-meson:
+msys2-mingw64-meson:
   variables:
-    MSYSTEM: "MINGW32"
+    MSYSTEM: "MINGW64"
     CHERE_INVOKING: "yes"
   stage: build
   tags:
@@ -80,10 +80,10 @@ msys2-mingw32-meson:
     paths:
       - "_build/meson-logs"
 
-msys2-mingw32-autotools:
+msys2-mingw64-autotools:
   when: manual
   variables:
-    MSYSTEM: "MINGW32"
+    MSYSTEM: "MINGW64"
     CHERE_INVOKING: "yes"
   stage: build
   tags: