Revert "fix(parsing): WEBP unnecessarily converted to PNG"

It turns out that Telegram cannot convert WEBP properly. In particular,
color space conversion seems broken.
Fixes #372

This reverts commit 3bafebf.

src/parsing/medium.py

@@ -64,9 +64,7 @@
 
 # Note:
 # One message can have 10 media at most, but there are some exceptions.
-# 1. A GIF (Animation) and WEBP (sent as a file) must occupy a SINGLE message.
-#   1a. A WEBP sent as a file will be shown just like a sticker.
-#   1b. Since some time in 2022, Telegram DC will convert any WEBP sent as an image to a JPG. Before that, same as (1a).
+# 1. A GIF (Animation) and webp (although as a file) must occupy a SINGLE message.
 # 2. Videos and Images can be mixed in a media group, but any other type of media cannot be in the same message.
 # 3. Images uploaded as MessageMediaPhoto will be considered as an image. While MessageMediaDocument not, it's a file.
 # 4. Any other type of media except Image must be uploaded as MessageMediaDocument.
@@ -348,14 +346,14 @@ def flushed_log():
                         self.valid = False
                         self.drop_silently = True
                         return False
-                    # force convert SVG to PNG
+                    # force convert WEBP/SVG to PNG
                     if (
                             self.content_type
-                            and any(keyword in self.content_type for keyword in ('svg', 'application'))
+                            and any(keyword in self.content_type for keyword in ('webp', 'svg', 'application'))
                     ):
                         # immediately fall back to 'wsrv.nl'
                         self.urls = [url for url in self.urls if url.startswith(env.IMAGES_WESERV_NL)]
-                        invalid_reasons.append('force convert SVG to PNG')
+                        invalid_reasons.append('force convert WEBP/SVG to PNG')
                         continue
                     # always invalid
                     if self.width + self.height > 10000:

src/parsing/post_formatter.py

@@ -536,7 +536,7 @@ async def parse_html(self):
                         medium.valid = False
                 elif not enclosure.type:
                     medium = File(enclosure.url)
-                elif 'svg' in enclosure.type:
+                elif any(keyword in enclosure.type for keyword in ('webp', 'svg')):
                     medium = Image(enclosure.url)
                     medium.url = construct_weserv_url_convert_to_2560_png(enclosure.url)
                 elif enclosure.type.startswith('image/gif'):