Load 'power_assert/context' at first in order to raise SyntaxError before defining ::PowerAssert

It is a hack for test-unit.

https://github.com/test-unit/test-unit/blob/f480a04ea0eb2be11f878051f280fc1de498afef/lib/test/unit/util/backtracefilter.rb#L15

Author: k-tsj

lib/power_assert.rb

@@ -17,9 +17,9 @@
   raise LoadError, 'Fully compatible TracePoint API required'
 end
 
-require 'power_assert/version'
-require 'power_assert/configuration'
 require 'power_assert/context'
+require 'power_assert/configuration'
+require 'power_assert/version'
 
 module PowerAssert
   POWER_ASSERT_LIB_DIR = File.dirname(caller_locations(1, 1).first.path)