[BUG FIX 5616904] Add transformers version restoration after PTQ for VILA (#525)

## What does this PR do?

**Type of change:** ? <!-- Use one of the following: Bug fix, new
feature, new example, new tests, documentation. -->
Bug fix

**Overview:** ?
Prompt user to manually install correct transformers version for VILA

## Usage
<!-- You can potentially add a usage example below. -->

```python
# Add a code snippet demonstrating how to use this
```

## Testing
<!-- Mention how have you tested your change if applicable. -->
```
CUDA_VISIBLE_DEVICES=0 bash -e scripts/huggingface_example.sh --model /models/VILA1.5-3b --quant fp8 --tp 1 --pp 1 --trust_remote_code --kv_cache_free_gpu_memory_fraction 0.5
```

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- **Make sure you read and follow [Contributor
guidelines](https://github.com/NVIDIA/TensorRT-Model-Optimizer/blob/main/CONTRIBUTING.md)**
and your commits are signed.
- **Is this change backward compatible?**: Yes/No <!--- If No, explain
why. -->
- **Did you write any new necessary tests?**: Yes/No
- **Did you add or update any necessary documentation?**: Yes/No
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[Changelog](https://github.com/NVIDIA/TensorRT-Model-Optimizer/blob/main/CHANGELOG.rst)?**:
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## Additional Information
<!-- E.g. related issue. -->

Signed-off-by: Yue <yueshen@nvidia.com>

Author: yueshen2016

examples/vlm_ptq/scripts/huggingface_example.sh

@@ -74,7 +74,16 @@ if [ -n "$KV_CACHE_QUANT" ]; then
 fi
 
 if [[ "${MODEL_NAME,,}" == *"vila"* ]]; then
-    # Install required dependency for VILA
+    # Check transformers version - must be <= 4.50.0
+    CURRENT_TRANSFORMERS_VERSION=$(pip show transformers | grep Version | cut -d' ' -f2)
+    if [ "$(printf '%s\n' "4.50.0" "$CURRENT_TRANSFORMERS_VERSION" | sort -V | head -n1)" = "4.50.0" ] && [ "$CURRENT_TRANSFORMERS_VERSION" != "4.50.0" ]; then
+        echo "ERROR: transformers version $CURRENT_TRANSFORMERS_VERSION is not supported." >&2
+        echo "VILA requires transformers<=4.50.0" >&2
+        echo "Please refer to examples/vlm_ptq/requirements-vila.txt for the supported versions." >&2
+        echo "You also need to download VILA repository from https://github.com/Efficient-Large-Model/VILA.git and checkout ec7fb2c264920bf004fd9fa37f1ec36ea0942db5" >&2
+        exit 1
+    fi
+
     pip install -r ../vlm_ptq/requirements-vila.txt
     # Clone original VILA repo
     if [ ! -d "$(dirname "$MODEL_PATH")/VILA" ]; then