patch 8.2.1767: Vim9: test fails with python support

Problem:    Vim9: test fails with python support.
Solution:   Use "let" in legacy function.

src/testdir/test_vim9_func.vim

@@ -831,7 +831,7 @@ enddef
 " recognized.
 func Test_function_python()
   CheckFeature python3
-  var py = 'python3'
+  let py = 'python3'
   execute py "<< EOF"
 def do_something():
   return 1

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1767,
 /**/
     1766,
 /**/