fix: download Fedora Silverblue iso instead of ociarchive file

[OhMyMndy]

Description

Make sure to download the iso for Fedora Silverblue instead of the ociarchive

Fixes #1257

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Packaging (updates the packaging)
• Documentation (updates the documentation)

Checklist:

• I have performed a self-review of my code
• I have tested my code in common scenarios and confirmed there are no regressions
• I have added comments to my code, particularly in hard-to-understand sections
• I have made corresponding changes to the documentation (remove if no documentation changes were required)

Result with this change:

$ ./quickget fedora 40 Silverblue
Downloading Fedora 40 Silverblue
- URL: https://fedora.mirrorservice.org/fedora/linux/releases/40/Silverblue/x86_64/iso/Fedora-Silverblue-ostree-x86_64-40-1.14.iso

Before the change

$ quickget fedora 40 Silverblue
Downloading Fedora 40 Silverblue
- URL: https://mirrors.xtom.ee/fedora/releases/40/Silverblue/x86_64/images/Fedora-Silverblue-40.1.14.ociarchive

[flexiondotorg]

Thank you!