[BUG] Bundles can be saved without file extension

[marticliment]

Please confirm these before moving forward

• I have searched for my issue and have not found a work-in-progress/duplicate/resolved issue.
• I have tested that this issue has not been fixed in the latest (beta or stable) release.
• I have checked the FAQ section for solutions.
• This issue is about a bug (if it is not, please use the correct template).

UniGetUI Version

N/A

Windows version, edition, and architecture

N/A

Describe your issue

Package bundles can be saved without an extension, making them useless unless the user manually adds the extension

Steps to reproduce the issue

N/A

UniGetUI Log

N/A

Package Managers Logs

N/A

Relevant information

No response

Screenshots and videos

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