Update .gitlab-ci.yml

.gitlab-ci.yml

@@ -2,6 +2,10 @@ stages:
   - build
   
 linux-stable:
+  tags:
+    - debian
+    - linux
+    
   image: gcc
     
   cache:
@@ -32,6 +36,9 @@ linux-stable:
     paths:
       - build/artifacts/
 darwin:
+  tags:
+    - xcode_7-2
+    - osx_10-11
   stage: build
   script: 
     - cores_to_use=$((`nproc`-2)); if (( $cores_to_use < 1 )); then cores_to_use=1; fi