chore: update NuttX version to 12.11 in CI workflows

The NuttX project released version 12.11 with improvements and bug fixes.
Updating the CI workflows to use the latest stable version ensures that
WAMR testing and compilation verification runs against the most current
NuttX release.

Updated 4 repository references total across 2 workflow files to point to
the new release branch.

Author: no1wudi

.github/workflows/compilation_on_nuttx.yml

@@ -88,14 +88,14 @@ jobs:
         uses: actions/checkout@v5
         with:
           repository: apache/nuttx
-          ref: releases/12.9
+          ref: releases/12.11
           path: nuttx
 
       - name: Checkout NuttX Apps
         uses: actions/checkout@v5
         with:
           repository: apache/nuttx-apps
-          ref: releases/12.9
+          ref: releases/12.11
           path: apps
 
       - name: Checkout WAMR

.github/workflows/spec_test_on_nuttx.yml

@@ -146,14 +146,14 @@ jobs:
         uses: actions/checkout@v5
         with:
           repository: apache/nuttx
-          ref: ${{ matrix.target_config.target == 'xtensa' && '985d395b025cf2012b22f6bb4461959fa6d87645' || 'releases/12.9' }}
+          ref: ${{ matrix.target_config.target == 'xtensa' && '985d395b025cf2012b22f6bb4461959fa6d87645' || 'releases/12.11' }}
           path: nuttx
 
       - name: Checkout NuttX Apps
         uses: actions/checkout@v5
         with:
           repository: apache/nuttx-apps
-          ref: ${{ matrix.target_config.target == 'xtensa' && '2ef3eb25c0cec944b13792185f7e5d5a05990d5f' || 'releases/12.9' }}
+          ref: ${{ matrix.target_config.target == 'xtensa' && '2ef3eb25c0cec944b13792185f7e5d5a05990d5f' || 'releases/12.11' }}
           path: apps
 
       - name: Checkout WAMR