Remove trailing whitespace in C++.gitignore

C++.gitignore

@@ -49,7 +49,7 @@ CMakeFiles/
 CMakeCache.txt
 cmake_install.cmake
 Makefile
-install_manifest.txt 
+install_manifest.txt
 compile_commands.json
 
 # Temporary files
@@ -66,4 +66,4 @@ vcpkg_installed/
 
 # test output & cache
 Testing/
-.cache/
+.cache/