Fix coverband:coverage_server rake task not being compatible with Rack 3 / Rackup

[obrie]

Rack::Server was extracted into a separate gem named rackup: rack/rack#1937

In this gem, Rack::Server is now Rackup::Server, which breaks the coverband:coverage_server rake task:

coverband/lib/coverband/utils/tasks.rb

Line 116 in edd2a90

Rack::Server.start app: Coverband::Reporters::Web.new,

This makes the current version of coverband incompatible with applications that use Rack 3. In addition to this fix, users must add rackup as a gem dependency if it's not already included in their gemset.

I've updated coverband to attempt to load either rackup/server or rack/server, preferring the former since this is what's expected for the latest version of Rack.

I wasn't sure what you might want to have in place in terms of tests, so that's a possible TODO here.

[danmayer]

thanks, I appreciate it