isso-dev.conf: Use dashed-case for misaka opts
isso-dev.conf: Use dashed-case for misaka opts

(This aligns isso-dev.conf with isso.conf as changed in
72e624bf6aeaeffa03a26f7d258561269ae54eec)

Misaka expects extensions and flags in `dashed-case` instead
of the legacy `snake_case` as of version 2.0.

See https://github.com/FSX/misaka/blob/v2.1.1/misaka/utils.py#L15-L37

posativ/isso,posativ/isso,posativ/isso,posativ/isso