tests/run-tests.py: Add a zephyr test target.

So that certain tests can be skipped when running on this target.  These
thread tests do not pass because the zephyr port cannot create more than 4
threads at once.

Signed-off-by: Damien George <damien@micropython.org>

tests/run-tests.py

@@ -637,6 +637,9 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         skip_tests.add("thread/thread_lock2.py")
         skip_tests.add("thread/thread_lock3.py")
         skip_tests.add("thread/thread_shared2.py")
+    elif args.target == "zephyr":
+        skip_tests.add("thread/stress_heap.py")
+        skip_tests.add("thread/thread_lock3.py")
 
     # Some tests shouldn't be run on pyboard
     if args.target != "unix":
@@ -1057,6 +1060,7 @@ the last matching regex is used:
         "qemu",
         "renesas-ra",
         "rp2",
+        "zephyr",
     )
     if args.list_tests:
         pyb = None