patch 8.2.1601: Vim9: cannot use 'true" with garbagecollect()

Problem:    Vim9: cannot use 'true" with garbagecollect().
Solution:   Use tv_get_bool(). (closes #6871)

src/evalfunc.c

@@ -2936,7 +2936,7 @@ f_garbagecollect(typval_T *argvars, typval_T *rettv UNUSED)
     // using Lists and Dicts internally.  E.g.: ":echo [garbagecollect()]".
     want_garbage_collect = TRUE;
 
-    if (argvars[0].v_type != VAR_UNKNOWN && tv_get_number(&argvars[0]) == 1)
+    if (argvars[0].v_type != VAR_UNKNOWN && tv_get_bool(&argvars[0]) == 1)
 	garbage_collect_at_exit = TRUE;
 }
 

src/testdir/test_vim9_func.vim

@@ -1285,6 +1285,10 @@ def Test_extend_return_type()
   assert_equal(6, res)
 enddef
 
+def Test_garbagecollect()
+  garbagecollect(true)
+enddef
+
 def Test_insert_return_type()
   let l = insert([2, 1], 3)
   let res = 0

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1601,
 /**/
     1600,
 /**/