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

ci_scripts/check_gcc_version.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# Check GCC version and install GCC 14 if needed
+check_gcc_version() {
+    if command -v gcc &> /dev/null; then
+        gcc_version=$(gcc -dumpversion | cut -d. -f1)
+        if [ "$gcc_version" -lt 14 ]; then
+            echo "GCC version $gcc_version detected. Installing GCC 14..."
+            sudo apt-get update
+            sudo apt-get install -y gcc-14
+            sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-14 100
+            echo "GCC 14 installed and set as default."
+        fi
+    fi
+}
+
+check_gcc_version