Upgrade libbrotli to v1.2.0

[illia-v]

Upgrade libbrotli to v1.2.0 which has a notable change for its Python library:

python: added Decompressor::can_accept_more_data method and optional
output_buffer_limit argument Decompressor::process;
that allows mitigation of unexpectedly large output;
reported by Charles Chan (https://github.com/charleswhchan)

[miurahr]

CI checks are failed because CI modernization #205 has never been merged.