Fix convention in gitlab config.

.gitlab-ci.yml

@@ -72,7 +72,7 @@ build-coq.8.19.0-dune:
   <<: *template
   <<: *branches_and_mr
   variables:
-    OPAM_PINS: "coq version 8.19.0 dune   version 3.15.2"
+    OPAM_PINS: "coq version 8.19.0   dune version 3.15.2"
     MAKE_TARGET: "dune"
 
 # The oldest version runs in MRs, without name mangling.