Subject charset issue

[dokime7]

Hi and thanks for this useful lib :)

I'm using 1.4.4 version

For improve deliverability it should be good to encode the message subject to utf-8 only when it contains no ascii char.
My issue is that Rspamd anti-spam add SUBJ_EXCESS_QP flag in this case and inscrease bad score.

See: Rspamd rule

Thanks

[theruziev]

I am glad to hear that.

I will try to fix that, but I need code review. I assign it to you for review.
I was read your other issue and will look too.

[dokime7]

Great!
If you want a quick implementation, I've submit a PR here for same issue:
https://github.com/caronc/apprise/pull/660/files#diff-a25a4da88bd4ee661599f260147d96e27fa3051b71ba4f4b88a87e5834cff3e8
just search for _get_charset method :)