BLTNBoard needs dark mode support

[aaronbrethorst]

I added support to this third party library, and our Carthage version just needs to be bumped to match. Support was added in 4.1.0: https://github.com/alexaubry/BulletinBoard/releases/tag/4.1.0

[alanb2718]

Version 4.1.0 of BulletinBoard seems to be working fine with dark mode. I tested it by setting alarms, which is a use of BulletinBoard in OneBusAway. (Are there other uses to test? I couldn't find any.)

What's the best way to bump the version? Cartfile includes the following:
github "aaronbrethorst/BulletinBoard" "private-deps"
However, this repository doesn't seem to be accessible to me. I just updated the version in Carthage/Checkouts/BulletinBoard to 4.1.0, which works fine although is ignoring the Cartfile command, so doesn't seem like the right thing longer term. So instead I tried changing the line in the Cartfile to github "alexaubry/BulletinBoard" ~> 4.1.0 and then did a carthage update. This also seems to work fine, but changes many files in Carthage/Checkouts since they seem to be lagging behind the current versions.

Also related to #78 (Update 3rd party libraries).

[aaronbrethorst]

Updating the Cartfile with github "alexaubry/BulletinBoard" ~> 4.1.0 and then doing a carthage update is correct. If you want to only want to change BulletinBoard, you can use the command

carthage update BulletinBoard

which is what I would do.

[aaronbrethorst]

(And alarms are the only use of this feature right now, but I'd love to replace the screen that requests location permissions with one of these too)

[alanb2718]

oops - I was going to have you review the change and merge, but pushed the merge button and ended up doing it. Anyway, the change follows what you suggested.

[aaronbrethorst]

All good and looks great, thanks!