attempt to fix building process #4

.gitlab-ci.yml

@@ -1,4 +1,4 @@
-image: gcc:latest
+image: rikorose/gcc-cmake:latest
 
 stages:
   - build
@@ -6,5 +6,4 @@ stages:
 build:
   stage: build
   script:
-    - apt update && apt install -y cmake
     - mkdir -p build bin debug && cd build && cmake -DCMAKE_BUILD_TYPE=Release .. && make -j