Update .gitlab-ci.yml file

.gitlab-ci.yml

@@ -5,7 +5,8 @@ stages:
   stage: build
   image: coqorg/${CI_JOB_NAME}
   before_script:
-    - if [ -n "${COMPILER_EDGE}" ]; then opam switch ${COMPILER_EDGE} && eval $(opam env); fi
+    - if [ -n "${COMPILER_EDGE}" ]; then opam switch ${COMPILER_EDGE}; fi
+    - eval $(opam env)
     - opam update -y
     - opam config list
     - opam repo list