replace json.loads with direct calls to JSONDecoder.decode

gallery_dl/util.py

@@ -204,6 +204,9 @@ def datetime_to_timestamp_string(dt):
         return ""
 
 
+json_loads = json._default_decoder.decode
+
+
 def dump_json(obj, fp=sys.stdout, ensure_ascii=True, indent=4):
     """Serialize 'obj' as JSON and write it to 'fp'"""
     json.dump(
@@ -513,7 +516,7 @@ def parse_inputfile(file, log):
                 continue
 
             try:
-                value = json.loads(value.strip())
+                value = json_loads(value.strip())
             except ValueError as exc:
                 log.warning("input file: unable to parse '%s': %s", value, exc)
                 continue