patch 9.0.1503: Luau files are not recognized

Problem:    Luau files are not recognized.
Solution:   Add a patter for Luau files. (Amaan Qureshi, closes #12317)
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 028982d..38db8a2 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -1190,6 +1190,9 @@
 " Lua
 au BufNewFile,BufRead *.lua			setf lua
 
+" Luau
+au BufNewFile,BufRead *.luau		setf luau
+
 " Luacheck
 au BufNewFile,BufRead .luacheckrc		setf lua
 
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index 8518770..a68d749 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -346,6 +346,7 @@
     \ 'lsl': ['file.lsl'],
     \ 'lss': ['file.lss'],
     \ 'lua': ['file.lua', 'file.rockspec', 'file.nse', '.luacheckrc', '.busted'],
+    \ 'luau': ['file.luau'],
     \ 'lynx': ['lynx.cfg'],
     \ 'lyrics': ['file.lrc'],
     \ 'm3build': ['m3makefile', 'm3overrides'],
diff --git a/src/version.c b/src/version.c
index 47b38cd..338399c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1503,
+/**/
     1502,
 /**/
     1501,