[MISC] Add tsalo as a BIDS maintainer

[tsalo]

Closes None.

Changes proposed:

• Add @tsalo as a BIDS maintainer.

[yarikoptic]

I don't remember what is the process on that (ie who can vote), but here is my +1 on that! ;)

[tsalo]

I joined about a month ago, but @sappelhoff asked me to open the PR recently (I had forgotten 🤦).

[sappelhoff]

@yarikoptic the process is not very formalized at the moment, anyone can reach out to the maintainers if they want to join the group. --> or the maintainers will reach out and ask somebody.

the non-finished maintainers guide is here: https://github.com/bids-standard/bids-specification/wiki/BIDS-Maintainers-Guide

[yarikoptic]

My comment was pretty much a question on either I (neither a "maintainer" nor part of steering committee... may be I should propose a "Whiners" or "Troublemakers" section to become a proud member of) could/should approve the PR? ;-)