Consolidate flake8 settings

Consolidates sane flake8 settings to pyproject with the Flake8-pyproject plugin.

Does not change logic of test workflow but allows base settings to live in pyproject for anyone using flake8 as an external linter (e.g. vscode)

Also fixes some flake8 errors that were not being picked up by current testing, mostly unused imports.

bdfr/site_downloaders/imgur.py

@@ -67,7 +67,7 @@ class Imgur(BaseDownloader):
             image_dict = re.search(outer_regex, chosen_script).group(1)
             image_dict = re.search(inner_regex, image_dict).group(1)
         except AttributeError:
-            raise SiteDownloaderError(f"Could not find image dictionary in page source")
+            raise SiteDownloaderError("Could not find image dictionary in page source")
 
         try:
             image_dict = json.loads(image_dict)

bdfr/site_downloaders/vreddit.py

@@ -2,14 +2,11 @@
 # -*- coding: utf-8 -*-
 
 import logging
-import tempfile
-from pathlib import Path
-from typing import Callable, Optional
+from typing import Optional
 
-import yt_dlp
 from praw.models import Submission
 
-from bdfr.exceptions import NotADownloadableLinkError, SiteDownloaderError
+from bdfr.exceptions import NotADownloadableLinkError
 from bdfr.resource import Resource
 from bdfr.site_authenticator import SiteAuthenticator
 from bdfr.site_downloaders.youtube import Youtube