patch 8.2.0373: type of term_sendkeys() is unknown

Problem:    Type of term_sendkeys() is unknown.
Solution:   Just return zero. (closes #5762)
diff --git a/src/terminal.c b/src/terminal.c
index 34316d8..30590b6 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -5746,13 +5746,12 @@
  * "term_sendkeys(buf, keys)" function
  */
     void
-f_term_sendkeys(typval_T *argvars, typval_T *rettv)
+f_term_sendkeys(typval_T *argvars, typval_T *rettv UNUSED)
 {
     buf_T	*buf = term_get_buf(argvars, "term_sendkeys()");
     char_u	*msg;
     term_T	*term;
 
-    rettv->v_type = VAR_UNKNOWN;
     if (buf == NULL)
 	return;
 
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 7bdabb8..8d32cbc 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -368,7 +368,11 @@
   call term_wait(buf)
   call term_sendkeys(buf, "exit\<CR>")
   call term_wait(buf)
-  call term_sendkeys(buf, ":q\<CR>")
+  let tsk_ret = term_sendkeys(buf, ":q\<CR>")
+
+  " check type of term_sendkeys() return value
+  echo type(tsk_ret)
+
   call StopVimInTerminal(buf)
   call delete('XTest_postponed')
   call delete('Xtext')
diff --git a/src/version.c b/src/version.c
index 2bf4b24..e55c261 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    373,
+/**/
     372,
 /**/
     371,