fix suspicious except statements

The "except ValueError as UnicodeDecodeError" looks very suspicious.
Commit change except to catch both exceptions.

https://fedorahosted.org/freeipa/ticket/5718

Reviewed-By: Tomas Babej <tbabej@redhat.com>

client/ipa-client-install

@@ -1798,7 +1798,7 @@ def update_ssh_keys(server, hostname, ssh_dir, create_sshfp):
                 continue
             try:
                 pubkey = SSHPublicKey(line)
-            except ValueError as UnicodeDecodeError:
+            except (ValueError, UnicodeDecodeError):
                 continue
             root_logger.info("Adding SSH public key from %s", filename)
             pubkeys.append(pubkey)