tests: fix "test-client.py" ignoring missing "NM" module

Fixes: 8959083784 ('tests: skip test in "test-client.py" if the pexepect dependency is not available')

src/tests/client/test-client.py

@@ -117,13 +117,17 @@ import gi
 
 try:
     from gi.repository import GLib
-except ImportError as e:
+except ImportError:
     GLib = None
 
 try:
     gi.require_version("NM", "1.0")
+except ValueError:
+    NM = None
+else:
+    try:
         from gi.repository import NM
-except ImportError as e:
+    except ImportError:
         NM = None
 
 try: