patch 9.0.0574: timer garbage collect test hangs on Mac M1

Problem:    Timer garbage collect test hangs on Mac M1.
Solution:   Properly check for Mac M1 and skip the test.
diff --git a/src/testdir/test_timers.vim b/src/testdir/test_timers.vim
index 98df6ff..f97808c 100644
--- a/src/testdir/test_timers.vim
+++ b/src/testdir/test_timers.vim
@@ -381,7 +381,12 @@
 " vgetc().
 func Test_nocatch_timer_garbage_collect()
   " FIXME: why does this fail only on MacOS M1?
-  CheckNotMacM1
+  try 
+    CheckNotMacM1
+  catch /Skipped/
+    let g:skipped_reason = v:exception
+    return
+  endtry
 
   " 'uptimetime. must be bigger than the timer timeout
   set ut=200