Added C standard gnu23 to the makefile (#288)

* Added C standard gnu23 to the makefile

* Added gnu23 standard to all test modue makefiles

* Added installation of latest gcc version to tests workflow

* Fixed typo in previous commit

* Made GCC 14 installation conditional and moved from the workflow to the script

* Extracted GCC version check to external script for CI and created tests README

* Added #!/bin/bash

* Make check_gcc_version.sh executable

.github/workflows/unit_tests_ci_workflow.yml

@@ -8,9 +8,14 @@ jobs:
   run-unit-tests:
     name: Run Unit Tests
     runs-on: ubuntu-latest
+
     steps:
+
       - name: Checkout repository
         uses: actions/checkout@v5
 
+      - name: Check and install GCC version
+        run: ./ci_scripts/check_gcc_version.sh
+
       - name: Run Unit Tests
         run: cd tests && ./run_tests.sh