fix yaml syntax

.gitlab-ci.yml

@@ -4,7 +4,7 @@ buildjob:
   tags:
   - coq
   script:
-  - make -j8 TIMED=y | tee /dev/stdout | egrep "[a-zA-Z0-9-_/]+ \(user: [0-9]" > build-time.txt
+  - "make -j8 TIMED=y | tee /dev/stdout | egrep '[a-zA-Z0-9-_/]+ \(user: [0-9]' > build-time.txt"
   artifacts:
     paths:
     - build-time.txt