🐛(y-provider) use CONVERSION_FILE_MAX_SIZE settings

The settings CONVERSION_FILE_MAX_SIZE was not used
in the y-provider, which caused a 413 Payload
Too Large error when trying to convert a file larger
than 500kb.
This commit updates the y-provider to use the
CONVERSION_FILE_MAX_SIZE settings, allowing it to
handle larger files without throwing an error.
CONVERSION_FILE_MAX_SIZE should follow the same
value as the one defined in the backend settings,
which is 20mb by default.

src/backend/impress/settings.py

@@ -736,7 +736,7 @@ class Base(Configuration):
 
     # Imported file settings
     CONVERSION_FILE_MAX_SIZE = values.IntegerValue(
-        20 * MB,  # 10MB
+        20 * MB,
         environ_name="CONVERSION_FILE_MAX_SIZE",
         environ_prefix=None,
     )