feat: double the number of reviews per API request

After some experimentation, I found out that 20 is the maximum page
size allowed by the App Store's API (the default is 10). So specify
that unless the `limit` passed to `reviews()` is lower than 20,
in which case we use that instead.

src/app_store_web_scraper/_entry.py

@@ -40,6 +40,8 @@ class AppReview:
     r'<meta name="web-experience-app/config/environment" content="(.+?)">',
 )
 
+_REVIEWS_PAGE_SIZE = 20
+
 
 class AppStoreEntry:
     """
@@ -75,11 +77,12 @@ def reviews(self, limit: int = 0) -> Iterator[AppReview]:
         params = {
             "platform": "web",
             "additionalPlatforms": "appletv,ipad,iphone,mac",
+            "sort": "-date",
+            "limit": str(min(limit, _REVIEWS_PAGE_SIZE))
+            if limit > 0
+            else str(_REVIEWS_PAGE_SIZE),
         }
 
-        if limit > 0:
-            params["limit"] = str(limit)
-
         query_string = urllib.parse.urlencode(params)
         url = f"{path}?{query_string}"
         review_count = 0