Resolving conv_bias bug

[ayoussf]

Hello,

In conv1d_x and conv1d_z, the bias argument was previously set as bias=conv_bias//2. Since conv_bias is a boolean, integer division always evaluates this to False, regardless of the default value. This has been corrected to bias=conv_bias.

However, since the released checkpoints were built with the bugged behaviour (i.e., bias=conv_bias//2), updating the default would break compatibility with those checkpoints. To maintain compatibility, the class default has been changed from conv_bias=True to conv_bias=False.