Revert "Raise error when blf GzipFile is requested"

This reverts commit 07e0510.

Author: j-c-cook

can/io/blf.py

@@ -11,7 +11,7 @@
 of uncompressed data each. This data contains the actual CAN messages and other
 objects types.
 """
-import gzip
+
 import struct
 import zlib
 import datetime
@@ -395,11 +395,6 @@ def __init__(
             speed and compression (currently equivalent to level 6).
         """
         mode = "rb+" if append else "wb"
-        if type(file) == gzip.GzipFile:
-            raise ValueError(
-                f"The BLFWriter is currently incompatible with "
-                f"{gzip.GzipFile.__name__}s. Try using a different zip format."
-            )
         try:
             super().__init__(file, mode=mode)
         except FileNotFoundError: