try fix CI: 1. pin coremltools 8.0b2; 2. refrain from defaulting stateful llama until CI machine upgraded to MacOS 15

Author: yifan_shen3

backends/apple/coreml/scripts/install_requirements.sh

@@ -24,7 +24,7 @@ rm -rf "$COREML_DIR_PATH/third-party"
 mkdir "$COREML_DIR_PATH/third-party"
 
 echo "${green}ExecuTorch: Cloning coremltools."
-git clone --depth 1 --branch 8.0b1 "https://github.com/apple/coremltools.git" $COREMLTOOLS_DIR_PATH
+git clone --depth 1 --branch 8.0b2 "https://github.com/apple/coremltools.git" $COREMLTOOLS_DIR_PATH
 cd $COREMLTOOLS_DIR_PATH
 
 STATUS=$?

backends/apple/coreml/test/test_coreml_partitioner.py

@@ -8,8 +8,6 @@
 
 import executorch.exir
 
-import pytest
-
 import torch
 import torchvision
 
@@ -91,10 +89,6 @@ def test_vit_skip_conv(self):
             if node.op == "call_function"
         ] == total
 
-    @pytest.mark.skipif(
-        "b" in ct.__version__ or ct.__version__ < "8.0",
-        reason="coremltools 8.0 or higher is required",
-    )
     def test_buffer(self):
         embedding_dim = 3
         max_seq_len = 2

examples/models/llama2/export_llama_lib.py

@@ -281,13 +281,7 @@ def build_args_parser() -> argparse.ArgumentParser:
     parser.add_argument("-V", "--vulkan", action="store_true")
     parser.add_argument("--mps", action="store_true")
     parser.add_argument("--coreml", action="store_true")
-    parser.add_argument(
-        "--coreml-disable-state",
-        dest="coreml_enable_state",
-        default=True,  # Enable this by default
-        action="store_false",
-        help="Delegate mutable buffer to Core ML state",
-    )
+    parser.add_argument("--coreml-enable-state", action="store_true")
     parser.add_argument(
         "--qnn",
         action="store_true",