Redundant version header removed from release PR descriptions

Release summaries are getting cleaner. By removing redundant information, developers reading automated changelogs can get straight to the updates without skipping past duplicate version titles.

The automated release PR generation script has been updated to strip out the top-level version header from the pull request body.

This was achieved by removing the explicit header injection during the markdown formatting phase. Alongside this functional tweak, the script underwent a routine formatting pass to compress multi-line arguments into cleaner, single-line statements.