Fix assert statement in aesCbcEncrypt() and aesCbcDecrypt()

[elliotwutingfeng]

According to the documentation

The paddedPlainText must be a multiple of the block size
(128-bits).

However the assert statement assert(128 == paddedPlaintext.length * 8); checks if paddedPlaintext is exactly 128-bits long.

They should be switched to assert(0 == paddedPlaintext.length % 16); (16 bytes = 128 bits)

[Ephenodrom]

@elliotwutingfeng
Hello, the PR was merged manually as this repository is a proxy. The fix will be available within the next version.
Thank you very much for your contribution.