Support some special Win7PE

INSTALL/grub/grub.cfg

@@ -130,6 +130,11 @@ function get_os_type {
 
 function vt_check_compatible_pe {
     #Check for PE without external tools
+    #set compatible if ISO file is less than 80MB
+    if [ $vt_chosen_size -gt 33554432 -a $vt_chosen_size -le 83886080 ]; then
+        set ventoy_compatible=YES
+    fi
+
     return
 }