title: Issue with tsvector search when using exclamation character
body: <p>I have a column (artist_name) containing names of artists in a table. I have another column (artist_name_search) which is auto populated by a trigger for full text search purpose.</p>
  
  <p>The requirement is that when searching for the word "Pink", I should be able to retrieve the artists "Pink" and "P!nk". I'm able to query each of these artist names individually using ts_vector and ts_query but could not get the combined results when searching for the word "Pink"</p>
  
  <p>Appreciate your help with solving this issue. Thanks!</p>
  
  <pre><code>--Definition of trigger that auto populates the tsvector column
  CREATE TRIGGER artists_tsvector_search
    BEFORE INSERT OR UPDATE OF artist_name
    ON artists
    FOR EACH ROW
  BEGIN
      NEW.artist_name_search = to_tsvector('english',NEW.artist_name);
    END;
  
  --Below query searches for the word "Pink"
  select artist_name_search, artist_name from artists where to_tsquery('Pink') @@ artist_name_search
  
  --Below query searches for the word "P!nk"
  select artist_name_search, artist_name from artists where to_tsquery('P\!nk') @@ artist_name_search 
  </code></pre>