Incorporate review suggestions

* Ues Python 3.10.
* Reorder keywords when extends keyword is used.
* Use full relative path to call exercise app.
* Use artifacts sub-key of needs keyword.
* Remove dependencies keyword from CI jobs in favour of needs sub-key
artifacts.
* Remove needs keywords that are not necessary because there are no
dependencies.

.gitlab-ci.yml

@@ -6,7 +6,7 @@
 ---
 
 default:
-  image: python:3.9
+  image: python:3.10
 
 .install_dependencies:
   before_script:
@@ -35,36 +35,37 @@ lint:
   interruptible: true
 
 build:gcc:
-  image: gcc:${VERSION}
   extends:
     - .install_dependencies
     - .compiler_versions
+  image: gcc:${VERSION}
   script:
     - cmake -S . -B build_gcc_${VERSION}
     - cmake --build build_gcc_${VERSION}
   artifacts:
     paths:
       - build_gcc_${VERSION}
-  needs: ["lint"]
   interruptible: true
 
 test:gcc:
-  image: gcc:${VERSION}
   extends:
     - .install_dependencies
     - .compiler_versions
+  image: gcc:${VERSION}
   script:
     - cd build_gcc_${VERSION} && ctest
-  dependencies: ["build:gcc"]
-  needs: ["build:gcc"]
+  needs:
+    - job: "build:gcc"
+      artifacts: true
   interruptible: true
 
 run:
   image: gcc:11
   script:
-    - cd build_gcc_11/bin/ && ./helloWorld
-  dependencies: ["build:gcc"]
-  needs: ["build:gcc", "test:gcc"]
+    - ./build_gcc_11/bin/helloWorld
+  needs:
+    - job: "build:gcc"
+      artifacts: true
   interruptible: true
 
 ...