patch 8.2.1572: Vim9: expand() does not take "true" as argument

Problem:    Vim9: expand() does not take "true" as argument.
Solution:   Use tv_get_bool_chk().  (closes #6819)
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 771e393..69f7816 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -2434,7 +2434,7 @@
     rettv->v_type = VAR_STRING;
     if (argvars[1].v_type != VAR_UNKNOWN
 	    && argvars[2].v_type != VAR_UNKNOWN
-	    && tv_get_number_chk(&argvars[2], &error)
+	    && tv_get_bool_chk(&argvars[2], &error)
 	    && !error)
 	rettv_list_set(rettv, NULL);
 
@@ -2458,7 +2458,7 @@
 	// When the optional second argument is non-zero, don't remove matches
 	// for 'wildignore' and don't put matches for 'suffixes' at the end.
 	if (argvars[1].v_type != VAR_UNKNOWN
-				    && tv_get_number_chk(&argvars[1], &error))
+				    && tv_get_bool_chk(&argvars[1], &error))
 	    options |= WILD_KEEP_ALL;
 	if (!error)
 	{