release(1.2.8): update mf6 version

Also added latest version of gsflow (v 2.3.0) and mfusg_gsi (v2.1.1).

autotest/conftest.py

@@ -1,8 +1,6 @@
 import re
 from importlib import metadata
 from pathlib import Path
-from platform import system
-from typing import List, Optional
 
 import matplotlib.pyplot as plt
 import pytest

autotest/test_cli_cmds.py

@@ -1,6 +1,4 @@
 import os
-import pathlib as pl
-import shutil
 import subprocess
 
 import pytest

autotest/test_gsflow.py

@@ -127,7 +127,7 @@ def run_gsflow(example, control_file, normal_message):
             normal_msg=normal_message,
         )
         if not success:
-            errmsg = f"could not run {control_file}"
+            print(f"could not run {control_file}")
     return success
 
 

autotest/test_mf6_existing_meson.py

@@ -1,5 +1,4 @@
 import os
-import shutil
 import sys
 
 import pytest