Fix bizarre libs path issue

When __dir__ contains a folder/directory containing a `:`, then the path gets mangled at some point. I could not figure out why, but adding the relative path works just fine (and, in fact, `t.libs` contains just `"lib"` which also is a relative path -- so it is consistent).

adsf-live/Rakefile

@@ -4,7 +4,7 @@ require 'rake/testtask'
 
 Rake::TestTask.new(:test) do |t|
   t.test_files = Dir[__dir__ + '/test/**/test_*.rb']
-  t.libs << (__dir__ + '/test')
+  t.libs << 'test'
   t.verbose = false
   t.warning = false # TODO: turn this back on when rack-livereload is fixed
 end

adsf/Rakefile

@@ -4,7 +4,7 @@ require 'rake/testtask'
 
 Rake::TestTask.new(:test) do |t|
   t.test_files = Dir[__dir__ + '/test/**/test_*.rb']
-  t.libs << (__dir__ + '/test')
+  t.libs << 'test'
   t.verbose = false
 end