Fix i3lock-fancy script for ImageMagick 7+ compatibility

[megvadulthangya]

Description

This PR updates the i3lock-fancy script to replace all instances of convert with magick for compatibility with ImageMagick 7+. In ImageMagick 7+, the traditional command-line tools (e.g., convert, mogrify) are prefixed with magick to avoid naming conflicts.

Changes Made

• Replaced all occurrences of convert with magick in /usr/bin/i3lock-fancy.
• This ensures the script works correctly on systems with ImageMagick 7 or later installed.

Why This Change?

ImageMagick 7+ requires the use of the magick prefix for its command-line tools. Without this change, the script fails with a "command not found" error on systems using newer versions of ImageMagick.

Testing

• Tested on Arch Linux (Garuda) with ImageMagick 7.1.1-20.
• The script now runs successfully after the change.

Additional Notes

• This is a minimal and non-breaking change.
• No additional dependencies are required, as magick is included with ImageMagick 7+.