fix: prevent multiple image windows for multi-face images

[gauris1104]

Summary

This PR fixes the issue where pil_image.show() was being called inside the face-processing loop.

Changes

• Moved pil_image.show() outside the for face_landmarks in face_landmarks_list loop.
• Ensured the image is displayed only once after all detected faces have been processed.

Result

• Prevents multiple image viewer windows from opening when an image contains multiple faces.
• Improves user experience without changing existing functionality.

Fixes #1666

[gauris1104]

I've submitted a PR for this issue: #1666

The fix moves pil_image.show() outside the face-processing loop so the image is displayed only once after all faces have been processed.