Use metadata to detect version of package (#4782)

Signed-off-by: Kebe <mail@kebe7jun.com>

python/sglang/check_env.py

 """Check environment configurations and dependency versions."""
 
-import importlib
+import importlib.metadata
 import os
 import resource
 import subprocess
@@ -59,9 +59,8 @@ def get_package_versions(packages):
     for package in packages:
         package_name = package.split("==")[0].split(">=")[0].split("<=")[0]
         try:
-            module = importlib.import_module(package_name)
-            if hasattr(module, "__version__"):
-                versions[package_name] = module.__version__
+            version = importlib.metadata.version(package_name)
+            versions[package_name] = version
         except ModuleNotFoundError:
             versions[package_name] = "Module Not Found"
     return versions