Add Github action to detect potential duplicate issues

[fbricon]

• Duplicate detection is only performed against the issue title.
• it's only triggered on new issues or when the issue title is edited

Signed-off-by: Fred Bricon fbricon@gmail.com

[fbricon]

So this pattern renders fine on the Web UI:

But the problem is emails are then missing the title, like

We have found issues that are potential duplicates:

• #6 (73%)
• #3 (85%)

If any of the issues listed above are a duplicate, please consider closing this issue & upvoting/commenting the original one.
Alternatively, if neither of the listed issues addresses your feature/bug, keep this issue open.

So if we use #{{ number }} {{title}} ({{ accuracy }}%), emails are fine but we get duplicate titles in the Web UI
and if we use [{{number}} {{title}}](#{{ number }}) ({{ accuracy }}%), emails and web UI both show the title, but we lose the issue status on the Web UI

[testforstephen]

We have found issues that are potential duplicates:

• #6 (73%)
• #3 (85%)

If any of the issues listed above are a duplicate, please consider closing this issue & upvoting/commenting the original one.
Alternatively, if neither of the listed issues addresses your feature/bug, keep this issue open.

Not having the title in email is fine for me. It's nice to have that. Eventually, the user has to jump to the duplicate issue to further check if it's a duplicate.