CMakeVersion.bash: Update sed expression for lower-case 'set'

Since commit 77543bde (Convert CMake-language commands to lower case,
2012-08-13) the CMakeVersion.cmake file contains lower-case 'set'
commands.  Teach CMakeVersion.bash to replace the lower-case name
instead of the old upper-case 'SET'.

Source/CMakeVersion.bash

@@ -3,5 +3,5 @@
 if test "x$1" = "x-f"; then shift ; n='*' ; else n='\{8\}' ; fi
 if test "$#" -gt 0; then echo 1>&2 "usage: CMakeVersion.bash [-f]"; exit 1; fi
 sed -i -e '
-s/\(^SET(CMake_VERSION_TWEAK\) [0-9]'"$n"'\(.*\)/\1 '"$(date +%Y%m%d)"'\2/
+s/\(^set(CMake_VERSION_TWEAK\) [0-9]'"$n"'\(.*\)/\1 '"$(date +%Y%m%d)"'\2/
 ' "${BASH_SOURCE%/*}/CMakeVersion.cmake"