patch 9.0.0772: the libvterm code is outdated

Problem:    The libvterm code is outdated.
Solution:   Include libvterm changes from revision 790 to 801.
diff --git a/src/libvterm/doc/seqs.txt b/src/libvterm/doc/seqs.txt
index 7f21367..02a9fe5 100644
--- a/src/libvterm/doc/seqs.txt
+++ b/src/libvterm/doc/seqs.txt
@@ -132,6 +132,7 @@
            1 or 2       =   block
            3 or 4       =   underline
            5 or 6       =   I-beam to left
+   x   CSI > q          = XTVERSION, request version string
  23x   CSI " q          = DECSCA, select character attributes
 123x   CSI r            = DECSTBM
    x   CSI s            = DECSLRM