ci: allow FreeBSD jobs to fail

The FreeBSD CI is flaky.

The CI is of only limited use if it fails spuriously. Until a glorious
future where GLib has active FreeBSD developers eager to debug its
testsuite, it would be pragmatic to accept the CI run as passing if all
other platforms are happy.
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3c8e7c8..0f9d96b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -361,6 +361,7 @@
     - meson ${MESON_COMMON_OPTIONS} --localstatedir=/var -Db_lundef=false -Diconv=external -Dxattr=false _build
     - ninja -C _build
     - bash -x ./.gitlab-ci/run-tests.sh
+  allow_failure: true
   artifacts:
     reports:
       junit: "_build/${CI_JOB_NAME}-report.xml"
@@ -391,6 +392,7 @@
     - bash -x ./.gitlab-ci/run-tests.sh
   except:
     - tags
+  allow_failure: true
   artifacts:
     reports:
       junit: "_build/${CI_JOB_NAME}-report.xml"