Switch dependency from deprecated bold package to new BOLDconnectR

[hjarnek]

The bold package has been taken off CRAN, and it seems unsure whether it's coming back at all (see discussion here). This makes installation of refdb fail. BOLD has now made their own R client, called BOLDconnectR, which probably will replace the old bold package, and is currently also the only package that supports BOLD's latest v5 API. It's probably time for the community to switch out all bold package dependencies for BOLDconnectR.