[pixeldrain] add 'api-key' option (#4839)

docs/configuration.rst

@@ -2553,6 +2553,14 @@ Description
     Download from video pins.
 
 
+extractor.pixeldrain.api-key
+----------------------------
+Type
+    ``string``
+Description
+    Your account's `API key <https://pixeldrain.com/user/api_keys>`__
+
+
 extractor.pixiv.include
 -----------------------
 Type

gallery_dl/extractor/pixeldrain.py

@@ -20,6 +20,11 @@ class PixeldrainExtractor(Extractor):
     root = "https://pixeldrain.com"
     archive_fmt = "{id}"
 
+    def _init(self):
+        api_key = self.config("api-key")
+        if api_key:
+            self.session.auth = ("", api_key)
+
     def parse_datetime(self, date_string):
         return text.parse_datetime(
             date_string, "%Y-%m-%dT%H:%M:%S.%fZ")