Added cache usage to ci

Adds cache to the pipeline

.gitlab-ci.yml

 image: node:16-buster
 
 cache:
+  key: ${CI_COMMIT_REF_SLUG}
   paths:
     - node_modules/
 
@@ -12,6 +13,11 @@ install_dependencies:
   stage: install
   script:
     - npm ci
+  cache:
+    key: ${CI_COMMIT_REF_SLUG}
+    paths:
+      - node_modules/
+    policy: push
 
 init_backend_server:
   stage: init
@@ -21,4 +27,9 @@ init_backend_server:
     - sleep 20
     - pkill node
   dependencies:
-    - install_dependencies
\ No newline at end of file
+    - install_dependencies
+  cache:
+    key: ${CI_COMMIT_REF_SLUG}
+    paths:
+      - node_modules/
+    policy: pull
\ No newline at end of file