patch 8.2.2842: Vim9: skip argument to searchpair() is not compiled

Problem:    Vim9: skip argument to searchpair() is not compiled.
Solution:   Add VAR_INSTR.
diff --git a/src/if_py_both.h b/src/if_py_both.h
index 9dbff1c..7f38e17 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -6425,6 +6425,7 @@
 	case VAR_VOID:
 	case VAR_CHANNEL:
 	case VAR_JOB:
+	case VAR_INSTR:
 	    Py_INCREF(Py_None);
 	    return Py_None;
 	case VAR_BOOL: