Add the missing blank lines

tests/start_test.py

@@ -19,10 +19,12 @@ ADDR_TO = "test@example.com"
 DB_NAME = "key-db.sqlite3"
 DEFAULT_PORT = 2525
 
+
 def fail(message):
     print(message, file=sys.stderr)
     sys.exit(1)
 
+
 def cp_tmp_file(path, executable=False):
     file = tempfile.NamedTemporaryFile(suffix=f"-{path.name}", delete=False)
     with open(path, mode="rb") as f:
@@ -156,6 +158,7 @@ def get_maildir():
     os.chmod(maildir.name, flags)
     return maildir
 
+
 def start_tests(test_dir, smtp_port, canonicalization):
     # Sending emails to OpenSMTPD
     maildir = get_maildir()