[glibmm] CI: Don't build everything with warnings=fatal

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 131a4c5ddc706f338cd9457a38b5f63145456a9d
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Wed Feb 16 13:44:25 2022 +0100

    CI: Don't build everything with warnings=fatal
    
    Build only glibmm with warnings=fatal.
    Select latest released version of libsigc++3.

 .gitlab-ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e1987b83..f8c1902f 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -50,10 +50,10 @@ build_deps:
     # Build and cache dependencies that can't be installed with apt.
     # Build libsigc++3
     - if test ! -d libsigc; then
-    - git clone --branch 3.0.7 --depth 1 https://github.com/libsigcplusplus/libsigcplusplus.git libsigc
+    - git clone --branch 3.2.0 --depth 1 https://github.com/libsigcplusplus/libsigcplusplus.git libsigc
     - cd libsigc
     - mkdir _build && cd _build
-    - meson --prefix=/usr --libdir=lib -Dwarnings=fatal -Dbuild-examples=false -Dbuildtype=release
+    - meson --prefix=/usr --libdir=lib -Dbuild-documentation=false -Dbuild-examples=false -Dbuildtype=release
     - meson compile
     - cd ../..
     - fi