cleanup: remove old deprecation approach

Remove no longer used code.

spec/radix/tree_spec.cr

@@ -1,25 +1,5 @@
 require "../spec_helper"
 
-# Silence deprecation warnings when running specs and allow
-# capture them for inspection.
-module Radix
-  class Tree(T)
-    @show_deprecations = false
-    @stderr : IO::Memory?
-
-    def show_deprecations!
-      @show_deprecations = true
-    end
-
-    private def deprecation(message)
-      if @show_deprecations
-        @stderr ||= IO::Memory.new
-        @stderr.not_nil!.puts message
-      end
-    end
-  end
-end
-
 # Simple Payload class
 record Payload
 

src/radix/tree.cr

@@ -462,11 +462,5 @@ module Radix
       (!different) &&
         (!key_reader.has_next? || _check_markers(key_reader.current_char))
     end
-
-    # :nodoc:
-    private def deprecation(message : String)
-      STDERR.puts message
-      STDERR.flush
-    end
   end
 end