[Minor] FindRagel.cmake - remove cmake min version

As now causes warning and main CMakeLists.txt min version is greater

cmake/FindRagel.cmake

@@ -41,9 +41,6 @@
 # /usr/share/cmake/Modules/FindFLEX.cmake
 # /usr/share/cmake/Modules/FindBISON.cmake
 
-# uses some features which are not available in 2.6
-cmake_minimum_required(VERSION 2.8)
-
 find_program(RAGEL_EXECUTABLE NAMES ragel DOC "path to the ragel executable")
 mark_as_advanced(RAGEL_EXECUTABLE)