tests : check the Python version (#7872)

ggml-ci

tests/test-json-schema-to-grammar.cpp

@@ -870,7 +870,7 @@ int main() {
         }
     });
 
-    if (getenv("LLAMA_PYTHON_AVAILABLE") || (std::system("python --version") == 0)) {
+    if (getenv("LLAMA_PYTHON_AVAILABLE") || (std::system("python -c \"import sys; exit(1) if sys.version_info < (3, 8) else print('Python version is sufficient')\"") == 0)) {
         test_all("Python", [](const TestCase & tc) {
             write("test-json-schema-input.tmp", tc.schema);
             tc.verify_status(std::system(
@@ -878,7 +878,7 @@ int main() {
             tc.verify(read("test-grammar-output.tmp"));
         });
     } else {
-        fprintf(stderr, "\033[33mWARNING: Python not found, skipping Python JSON schema -> grammar tests.\n\033[0m");
+        fprintf(stderr, "\033[33mWARNING: Python not found (min version required is 3.8), skipping Python JSON schema -> grammar tests.\n\033[0m");
     }
 
     if (getenv("LLAMA_NODE_AVAILABLE") || (std::system("node --version") == 0)) {