.gitlab-ci.yml: Use the same version of the docker image for all jobs

.gitlab-ci.yml

-image: buildstream/testsuite-debian:9-master-102-9067e269
+image: buildstream/testsuite-debian:9-master-112-a9f63c5e
 
 cache:
   key: "$CI_JOB_NAME-"
@@ -89,11 +89,11 @@ source_dist:
     - coverage-linux/
 
 tests-debian-9:
-  image: buildstream/testsuite-debian:9-master-102-9067e269
+  image: buildstream/testsuite-debian:9-master-112-a9f63c5e
   <<: *linux-tests
 
 tests-fedora-27:
-  image: buildstream/testsuite-fedora:27-master-102-9067e269
+  image: buildstream/testsuite-fedora:27-master-112-a9f63c5e
   <<: *linux-tests
 
 tests-fedora-28:
@@ -107,7 +107,7 @@ tests-ubuntu-18.04:
 tests-unix:
   # Use fedora here, to a) run a test on fedora and b) ensure that we
   # can get rid of ostree - this is not possible with debian-8
-  image: buildstream/testsuite-fedora:27-master-102-9067e269
+  image: buildstream/testsuite-fedora:27-master-112-a9f63c5e
   stage: test
   variables:
     BST_FORCE_BACKEND: "unix"