Bump fastobo-validator to v0.4.0

[althonos]

The new release:

• Adds support for line comments (i.e. comments that span on their own line, as opposed to comments at the end of a clause line, which was already supported).
• Adds a additional check (disabled by default) to ensure obsoletion clauses (replaced_by and consider) only appear in obsolete entities (-O flag to the CLI).

[matentzn]

Thanks a ton @althonos