Another try at fixing the PR template link

[jeffcharles]

Description of the change

Remove the leading / on the link to get a different URL to render.

Why am I making this change?

The attempt at a fix didn't work. Instead it's linking to https://github.com/blob/main/.... I'm guessing based on the previous relative link behaviour that removing the leading / will get the link to render correctly.

Checklist

• I've updated the relevant CHANGELOG files if necessary. Changes to javy-cli and javy-core do not require updating CHANGELOG files.
• I've updated the relevant crate versions if necessary. Versioning policy for library crates
• I've updated documentation including crate documentation if necessary.