katifetch: update template to version 13.1 and fix install hooks

[ximimoments]

Summary

This PR updates the katifetch template in Void Linux packages.
Changes include:

• Fixed build issues on x86_64
• Added proper do_install commands for scripts
• Updated template metadata to reflect current version 13.1
• Adjusted hooks for pre/post install to match Void packaging standards

Testing the changes

• I built and installed katifetch locally in masterdir-x86_64
• Verified the executable runs and displays system information correctly
• Tested in WSL2 Void Linux x86_64 environment

Notes

• This update ensures compatibility with latest Void Linux hostdir structure
• No new dependencies introduced
• All scripts and assets preserved

Local build testing

• Built locally for native x86_64 architecture

[Bnyro]

This unfortunately doesn't seem to match the package requirements (https://github.com/void-linux/void-packages/blob/master/CONTRIBUTING.md#package-requirements). Also, the commit message should be New package: katifetch-13.1.

[Bnyro]

Why on earth are you setting the build style to gnu-makefile to package a shell script? Just remove this line.

Also, you skip do_build and override do_install, so the build style doesn't do anything

[Bnyro]

Suggested change

	do_build() {
	:
	}