fix: Postinstall script cannot be executed

[Losses]

Description

This pull request addresses the issue of Windows compatibility for the postinstall script in the shard.yml file. The original script was not supported on Windows, which caused installation issues for users on that platform.

Changes Made

• Replaced the original postinstall script with a Crystal script to ensure compatibility across different operating systems, including Windows.

New postinstall Script

The new script is as follows:

sam_cr_path = "../../sam.cr"
template_path = "examples/sam.template"

if !File.exists?(sam_cr_path)
  File.copy(template_path, sam_cr_path)
end

Benefits

• Ensures that the postinstall script runs smoothly on Windows.
• Leverages Crystal's standard library for file operations, making the script more portable and easier to maintain.

Testing

• Verified that the sam.cr file is correctly copied from the template if it does not already exist.

Related Issues

• Windows Support for postinstall Script in shard.yml #24

Thank you for considering this improvement. Looking forward to your feedback.