patch 9.0.1200: AppVeyor builds with an old Python version

Problem:    AppVeyor builds with an old Python version.
Solution:   Switch from Python 3.8 to 3.11. (Christopher Plewright,
            closes #11814)

ci/appveyor.bat

@@ -4,6 +4,20 @@
 setlocal ENABLEDELAYEDEXPANSION
 cd %APPVEYOR_BUILD_FOLDER%
 
+:: Python3
+set PYTHON3_VER=311
+set PYTHON3_RELEASE=3.11.1
+set PYTHON3_URL=https://www.python.org/ftp/python/%PYTHON3_RELEASE%/python-%PYTHON3_RELEASE%-amd64.exe
+set PYTHON3_DIR=C:\python%PYTHON3_VER%-x64
+
+if not exist downloads mkdir downloads
+
+:: Python 3
+if not exist %PYTHON3_DIR% (
+  call :downloadfile %PYTHON3_URL% downloads\python3.exe
+  cmd /c start /wait downloads\python3.exe /quiet TargetDir=%PYTHON3_DIR%  Include_pip=0 Include_tcltk=0 Include_test=0 Include_tools=0 AssociateFiles=0 Shortcuts=0 Include_doc=0 Include_launcher=0 InstallLauncherAllUsers=0
+)
+
 cd src
 
 echo "Building MSVC 64bit console Version"
@@ -22,7 +36,7 @@ if "%FEATURE%" == "HUGE" (
     nmake -f Make_mvc.mak CPU=AMD64 ^
         OLE=no GUI=yes IME=yes ICONV=yes DEBUG=no POSTSCRIPT=yes ^
         PYTHON_VER=27 DYNAMIC_PYTHON=yes PYTHON=C:\Python27-x64 ^
-        PYTHON3_VER=38 DYNAMIC_PYTHON3=yes PYTHON3=C:\Python38-x64 ^
+        PYTHON3_VER=%PYTHON3_VER% DYNAMIC_PYTHON3=yes PYTHON3=%PYTHON3_DIR% ^
         FEATURES=%FEATURE%
 ) ELSE (
     nmake -f Make_mvc.mak CPU=AMD64 ^
@@ -40,3 +54,17 @@ echo "version output MSVC console"
 echo "version output MSVC GUI"
 type ver_msvc.txt || exit 1
 cd ..
+
+goto :eof
+:: ----------------------------------------------------------------------
+
+:downloadfile
+:: call :downloadfile <URL> <localfile>
+if not exist %2 (
+	curl -f -L %1 -o %2
+)
+if ERRORLEVEL 1 (
+	rem Retry once.
+	curl -f -L %1 -o %2 || exit 1
+)
+@goto :eof

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1200,
 /**/
     1199,
 /**/