removing the public head "libetpan_version.h" from the public header installation list since it no longer exists.

build-windows/build_headers.list

@@ -151,7 +151,6 @@ src\low-level\smtp\mailsmtp_socket.h
 src\low-level\smtp\mailsmtp_ssl.h
 src\low-level\smtp\mailsmtp_types.h
 src\main\libetpan.h
-src\main\libetpan_version.h
 src\windows\win_etpan.h
 build-windows\libetpan-config.h
 build-windows\libetpan_version.h