Install Meson from backports.

Toolbx requires atleast 0.58 but Bullseye has 0.56.1.

.gitlab-ci.yml

@@ -10,6 +10,10 @@ build:
   stage: build
   image: buildpack-deps:bullseye
   before_script:
+    - >-
+      echo
+      'deb http://deb.debian.org/debian bullseye-backports main' >>
+      /etc/apt/sources.list
     - apt-get update
     - >-
       apt-get install -y
@@ -17,7 +21,7 @@ build:
       cmake
       golang
       go-md2man
-      meson
+      meson/bullseye-backports
       podman
       shellcheck
       systemd