Update CI pipeline to use more recent versions

* Use python:3.11 image and gcc:11 and gcc:12 image in CI pipeline.
* GoogleTest v1.13.0 supports only C++ >= 14. This requirement is
  not met with gcc:10, hence remove CI jobs with gcc:10 image.

.gitlab-ci.yml

@@ -12,7 +12,7 @@ stages:
   - run
 
 default:
-  image: python:3.10
+  image: python:3.11
 
 .install_dependencies:
   before_script:
@@ -22,7 +22,7 @@ default:
 .compiler_versions:
   parallel:
     matrix:
-      - VERSION: [ "10", "11", "12" ]
+      - VERSION: [ "11", "12" ]
 
 license_compliance:
   stage: lint
@@ -65,10 +65,10 @@ test:gcc:
     - "build:gcc"
 
 run:
-  image: gcc:11
+  image: gcc:12
   stage: run
   script:
-    - ./build_gcc_11/bin/helloWorld
+    - ./build_gcc_12/bin/helloWorld
   dependencies:
     - "build:gcc"