[GitLabCI] Fix missing $ after INSTALl_PATH.

.gitlab/ci/build.gitlab-ci.yml

@@ -16,13 +16,13 @@ build:ubuntu_cpp:
     - git clone $REPO_URL $MODULE_NAME
     - mkdir -p $MODULE_NAME/build
     - cd $MODULE_NAME/build
-    - cmake -DCMAKE_INSTALL_PREFIX:PATH=INSTALL_PATH -DCMAKE_BUILD_TYPE=Debug -DWERROR=ON ..
+    - cmake -DCMAKE_INSTALL_PREFIX:PATH=$INSTALL_PATH -DCMAKE_BUILD_TYPE=Debug -DWERROR=ON ..
     
     - cd ../..
     
     # Build current module
     - cd build_cpp
-    - cmake -DCMAKE_INSTALL_PREFIX:PATH=INSTALL_PATH -DCMAKE_BUILD_TYPE=Debug -DWERROR=ON ..
+    - cmake -DCMAKE_INSTALL_PREFIX:PATH=$INSTALL_PATH -DCMAKE_BUILD_TYPE=Debug -DWERROR=ON ..
     - make -j4 all install
 
   artifacts: