Add model merger to save checkpoints in the format of .safetensor and push them to the huggingface (#262)

This PR introduces a new script, `scripts/model_merger.py`, which
enables the conversion of model checkpoints saved in `.pt` format to the
`.safetensors` format. The script also includes functionality to
optionally push the converted model to Hugging Face Hub.

### Changes:
1. Added `scripts/model_merger.py` to handle the conversion process.
2. Implemented support for `.pt` to `.safetensors` transformation.
3. Added an option to push the converted model to Hugging Face Hub if
required.