feat: change license from MIT to MIT + Apache 2.0 (from 2020 onwards)

[vmx]

In order to unify the licenses across several multiformats repositories I propose changing the license to an MIT + Apache 2.0 dual license.

In order to make this change, it needs to be approved by all contributors.

If you agree with such a license change, please respond to this PR with:

I license past and future contributions under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.

This is a follow up from #25. I created a new PR as I didn't want to create notify spam to the ones that already agreed.

This also leads to some notification spam, I'm sorry for that, but I think that's the best/easiest/most transparent way of doing it.

[vmx]

I hereby ping all the current contributors since April 2020 (@Arqu @woss @edouardparis @galargh @hanabi1224 @Kubuxu @kayabaNerve @mattheworris @mxinden @paolobarbolini @Stebalien @thomaseizinger @tyshko5 @vmx) to please agree to the license change with replying to this PR with:

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[vmx]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[paolobarbolini]

I license past and future contributions under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.

[hanabi1224]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[mxinden]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[mattheworris]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[Stebalien]

I license past and future contributions under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.

[Arqu]

I license past and future contributions under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.

[thomaseizinger]

I license past and future contributions under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.

[galargh]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[edouardparis]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[Kubuxu]

I license past and future contributions under the dual MIT/Apache-2.0 license, allowing licensees to choose either at their option.

[kayabaNerve]

I license contributions to multiformats/rust-cid predating July 1st, 2025 under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.

I'm unsure what contributions I've made in the past but that should be sufficient. If it isn't, please let me know and I'll do my best to issue the necessary statement (as I unfortunately can't reasonably use the requested format).

Thank you for asking permission from contributors and doing this properly.

[woss]

I license past and future contributions under the dual MIT/Apache-2.0 license,
allowing licensees to choose either at their option.