patch 9.0.2101: CI: test_termdebug may still fail

Problem:  CI: test_termdebug may still fail
Solution: use term_wait() to make it more robust

closes: #13529

Signed-off-by: shane.xb.qian <shane.qian@foxmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_termdebug.vim

@@ -96,6 +96,7 @@ func Test_termdebug_basic()
     bw!
   endif
   set columns=160
+  call term_wait(gdb_buf)
   let winw = winwidth(0)
   Var
   if winwidth(0) < winw
@@ -113,6 +114,7 @@ func Test_termdebug_basic()
     bw!
   endif
   set columns&
+  call term_wait(gdb_buf)
 
   wincmd t
   quit!

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2101,
 /**/
     2100,
 /**/