fix: missing exception and unused import

tools/keygen

@@ -42,7 +42,6 @@ import os
 import re
 import struct
 import sys
-import time
 import warnings
 
 __version__='0.0.5'
@@ -610,7 +609,7 @@ class keygen:
         try:
             self.ed25519_seed_bytes_from_duniterpy()
             self.ed25519_from_seed_bytes()
-        except:
+        except Exception as e:
             log.error(f'Unable to get ed25519 from duniterpy: {e}')
             self._cleanup()
             exit(2)