Tests: Revise message in RunCMake.CommandLine -Wdev case

Use more prose-like capitalization.

Tests/RunCMake/CommandLine/Wdev-stderr.txt

@@ -1,5 +1,5 @@
 ^CMake Warning \(dev\) at Wdev.cmake:1 \(message\):
-  Some Author Warning
+  Some author warning
 Call Stack \(most recent call first\):
   CMakeLists.txt:3 \(include\)
 This warning is for project developers.  Use -Wno-dev to suppress it.

Tests/RunCMake/CommandLine/Wdev.cmake

@@ -1,4 +1,4 @@
-message(AUTHOR_WARNING "Some Author Warning")
+message(AUTHOR_WARNING "Some author warning")
 
 # with -Wdev this will also cause an AUTHOR_WARNING message, checks that
 # messages issued outside of the message command, by other CMake commands, also

Tests/RunCMake/CommandLine/Wno-dev.cmake

@@ -1,4 +1,4 @@
-message(AUTHOR_WARNING "Some Author Warning")
+message(AUTHOR_WARNING "Some author warning")
 
 # without -Wno-dev this will also cause an AUTHOR_WARNING message, checks that
 # messages issued outside of the message command, by other CMake commands, also