Use ornament quotations for Quotation’s pure_content

The result is visually similar to what the web UI uses, and
avoids any ambiguity with common quote characters used by the
quotation itself.

The characters introduced are:

- HEAVY DOUBLE COMMA QUOTATION MARK ORNAMENT U+275E
- HEAVY DOUBLE TURNED COMMA QUOTATION MARK ORNAMENT U+275D

bookwyrm/models/status.py

@@ -357,8 +357,8 @@ class Quotation(BookStatus):
     @property
     def pure_content(self):
         """indicate the book in question for mastodon (or w/e) users"""
-        quote = re.sub(r"^<p>", '<p>"', self.quote)
-        quote = re.sub(r"</p>$", '"</p>', quote)
+        quote = re.sub(r"^<p>", "<p>❝", self.quote)
+        quote = re.sub(r"</p>$", "❞</p>", quote)
         if self.position_mode == "PG" and self.position and (self.position > 0):
             return_value = (
                 f'{quote} <p>-- <a href="{self.book.remote_id}">'