CI: Switch to new Windows runners

They use powershell instead of cmd.exe, use the tag win32-ps instead of win32,
and run Windows 2016 instead of 2012r2.

The old runners will be switched off in the comming weeks.

.gitlab-ci.yml

@@ -99,12 +99,12 @@ release-build:
 .mingw-defaults: &mingw-defaults
   stage: build
   tags:
-    - win32
+    - win32-ps
   script:
     - C:\msys64\usr\bin\pacman --noconfirm -Syyuu
     - C:\msys64\usr\bin\bash -lc "bash -x ./.gitlab-ci/test-msys2.sh"
   cache:
-    key: "%CI_JOB_NAME%"
+    key: "${env:CI_JOB_NAME}"
     <<: *cache-paths
 
 msys2-mingw32:

.gitlab-ci/test-msys2.sh

@@ -34,7 +34,7 @@ pacman --noconfirm -S --needed \
     mingw-w64-$MSYS2_ARCH-shared-mime-info
 
 # https://gitlab.gnome.org/GNOME/gtk/issues/2243
-wget "https://gitlab.gnome.org/creiter/gitlab-ci-win32-runner/raw/master/pango/mingw-w64-$MSYS2_ARCH-pango-1.44.7-1-any.pkg.tar.xz"
+wget "https://gitlab.gnome.org/creiter/gitlab-ci-win32-runner-v2/raw/master/pango/mingw-w64-$MSYS2_ARCH-pango-1.44.7-1-any.pkg.tar.xz"
 pacman --noconfirm -U "mingw-w64-$MSYS2_ARCH-pango-1.44.7-1-any.pkg.tar.xz"
 
 mkdir -p _ccache