patch 8.2.1020: popupwin test fails in the GUI

Problem:    Popupwin test fails in the GUI.
Solution:   Send GUI byte sequence for <C-S-a>.
diff --git a/src/testdir/test_popupwin.vim b/src/testdir/test_popupwin.vim
index b6f718c..42f4256 100644
--- a/src/testdir/test_popupwin.vim
+++ b/src/testdir/test_popupwin.vim
@@ -3349,7 +3349,11 @@
 
   if has('unix')
     " with modifyOtherKeys <M-S-a> does not include a modifier sequence
-    call feedkeys("\<Esc>[27;4;65~", 'Lx!')
+    if has('gui_running')
+      call feedkeys("\x9b\xfc\x08A", 'Lx!')
+    else
+      call feedkeys("\<Esc>[27;4;65~", 'Lx!')
+    endif
     call assert_equal([0xc3, 0x81], g:bytes)
   endif
 
diff --git a/src/version.c b/src/version.c
index 5d7e451..b9e6d5b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1020,
+/**/
     1019,
 /**/
     1018,