patch 8.0.0961: the script to build the installer does not include winpty

Problem:    The script to build the installer does not include winpty.
Solution:   Add winpty32.dll and winpty-agent.exe like diff.exe

nsis/gvim.nsi

@@ -191,13 +191,16 @@ Section "Vim executables and runtime files"
 	File ${VIMSRC}\vimrun.exe
 	File /oname=tee.exe ${VIMSRC}\teew32.exe
 	File /oname=xxd.exe ${VIMSRC}\xxdw32.exe
-	File ${VIMTOOLS}\diff.exe
 	File ${VIMRT}\vimtutor.bat
 	File ${VIMRT}\README.txt
 	File ..\uninstal.txt
 	File ${VIMRT}\*.vim
 	File ${VIMRT}\rgb.txt
 
+	File ${VIMTOOLS}\diff.exe
+	File ${VIMTOOLS}\winpty32.dll
+	File ${VIMTOOLS}\winpty-agent.exe
+
 	SetOutPath $0\colors
 	File ${VIMRT}\colors\*.*
 

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    961,
 /**/
     960,
 /**/