fix: avoid validation error when issue body is empty

### Motivation https://github.com/ScoopInstaller/GithubActions/blob/63f20efd5d6f876b16fbe2bc95428821b6051c0e/src/Action/Issue/Extraction.psm1#L77-L78 The mandatory parameter validation was failing because the issue body could be empty. ``` INFO: Issue initialized Detected issue type: Decompression/Extraction error. Show-ExtractionHelpDoc: Cannot bind argument to parameter 'IssueBody' because it is an empty string. INFO: Issue finished ``` ### Related Issues/PRs - #78 - https://github.com/ScoopInstaller/Main/issues/8014 - https://github.com/ScoopInstaller/Main/actions/runs/25908638224/job/76147869244 <!-- This is an auto-generated comment: release notes by coderabbit.ai --> ## Summary by CodeRabbit ## Release Notes * **Enhancements** * Improved parameter handling to accept empty string values in issue body field processing. <!-- review_stack_entry_start --> [](https://app.coderabbit.ai/change-stack/ScoopInstaller/GithubActions/pull/80) <!-- review_stack_entry_end --> <!-- end of auto-generated comment: release notes by coderabbit.ai -->