Make config parser and its tests flake8-clean

Drop unused imports, drop extra empty lines, replace a wildcard
import with a series of specific imports.

Fixes: abd77e4d ("Add configuration de/serialisation code")

Signed-off-by: Andrej Shadura <andrew.shadura@collabora.co.uk>

obs_proxy/config.py

@@ -17,7 +17,7 @@ from configparser import ConfigParser
 from dataclasses import dataclass, is_dataclass
 from logging import error
 from pathlib import Path
-from typing import Iterable, Mapping
+from typing import Mapping
 
 HTTP_TIMEOUT = 20 * 60
 
@@ -184,12 +184,10 @@ class Config:
             cachedir=cachedir,
         )
 
-
     def __post_init__(self):
         if self.tracedir:
             self.tracedir.mkdir(parents=True, exist_ok=True)
 
-
     def as_dict(self):
         def serialize(o):
             if is_dataclass(o):
@@ -204,7 +202,6 @@ class Config:
 
         return serialize(self)
 
-
     def update_from_dict(self, d):
         def deserialize(o, c, d):
             if is_dataclass(o):

tests/test_config.py

 import io
 
-import pytest
-from obs_proxy.config import *
+from obs_proxy.config import (
+    Config,
+    AuthConfig,
+    BackendConfig,
+    ClientConfig,
+    ServerConfig,
+)
 
 
 basic_config = """
@@ -124,12 +129,12 @@ def test_mini_config():
             insecure=False,
             buffer_uploads=False,
             keyfile=None,
-            certfile=None
+            certfile=None,
         ),
         client=ClientConfig(
             host='0.0.0.0',
             port=5000,
-            buffer_uploads=True
+            buffer_uploads=True,
         ),
         auth=AuthConfig(
             username='luser',
@@ -138,7 +143,7 @@ def test_mini_config():
         ),
         backend=BackendConfig(
             srcserver_uri=None,
-            repserver_uri=None
+            repserver_uri=None,
         ),
         worker_ports=None,
         debug=False,