Using stable branch for NuttX relative CI (#2872)

.github/workflows/compilation_on_nuttx.yml

@@ -108,12 +108,14 @@ jobs:
         uses: actions/checkout@v3
         with:
           repository: apache/incubator-nuttx
+          ref: releases/12.3
           path: nuttx
 
       - name: Checkout NuttX Apps
         uses: actions/checkout@v3
         with:
           repository: apache/incubator-nuttx-apps
+          ref: releases/12.3
           path: apps
 
       - name: Checkout WAMR

.github/workflows/spec_test_on_nuttx.yml

@@ -121,12 +121,14 @@ jobs:
         uses: actions/checkout@v3
         with:
           repository: apache/incubator-nuttx
+          ref: releases/12.3
           path: nuttx
 
       - name: Checkout NuttX Apps
         uses: actions/checkout@v3
         with:
           repository: apache/incubator-nuttx-apps
+          ref: releases/12.3
           path: apps
 
       - name: Checkout WAMR