Fix bug in title/url blocking regex (#969)

Fix the exception `AttributeError: 'Filter' object has no attribute 'block_url'`
introduced in this commit [1].

`self.block_title` and `self.block_url` were members of the Filter
object[2], but not anymore after commit [1].

This bug can be reproduced with setting WHOOGLE_CONFIG_BLOCK_URL to a
non-empty string.

[1] 10a15e06e1
[2] 284a8102c8

app/filter.py

@@ -225,7 +225,7 @@ class Filter:
     def remove_block_titles(self) -> None:
         if not self.main_divs or not self.config.block_title:
             return
-        block_title = re.compile(self.block_title)
+        block_title = re.compile(self.config.block_title)
         for div in [_ for _ in self.main_divs.find_all('div', recursive=True)]:
             block_divs = [_ for _ in div.find_all('h3', recursive=True)
                           if block_title.search(_.text) is not None]
@@ -234,7 +234,7 @@ class Filter:
     def remove_block_url(self) -> None:
         if not self.main_divs or not self.config.block_url:
             return
-        block_url = re.compile(self.block_url)
+        block_url = re.compile(self.config.block_url)
         for div in [_ for _ in self.main_divs.find_all('div', recursive=True)]:
             block_divs = [_ for _ in div.find_all('a', recursive=True)
                           if block_url.search(_.attrs['href']) is not None]