Modify test_chacha20.py

Author: Susmita-Chakrabarty

pydatastructs/crypto/tests/test_chacha20.py

@@ -2,7 +2,7 @@
 import string
 from pydatastructs.crypto.ChaCha20 import ChaCha20
 
-VALID_KEY = b"\x00" *32
+VALID_KEY = B"\x00" *32
 assert len(VALID_KEY) == 32, "VALID_KEY must be exactly 32 bytes"
 VALID_NONCE = B"\x00" * 12
 assert len(VALID_NONCE) == 12, "VALID_NONCE must be exactly 12 bytes"