Header cells ignore style about pytablewriter

[shawalli]

I tried to dig in to figure out where this was happening in the code, but I got a bit confused when trying to trace the writing code

[thombashi]

Thank you for your feedback.

In the current implementation, no styles other than colors are applied to headers.
In a future version, other styles might also be applicable to headers.

[thombashi]

pytablewriter 1.2.0 or later can apply styles to headers by style filters.