tests(sinsemilla): Minor changes to sinsemilla tests

[oxarbitrage]

Motivation

I was checking sinsemilla zebra implementation and i found 2 minor things i will like to change so i am pushing this PR, they are trivial things:

• Group the tests together so a user interested in the sincemila implementation can run cargo test sinsemilla.
• Replace an old link.

PR Author Checklist

Check before marking the PR as ready for review:

• Will the PR name make sense to users?
• Does the PR have a priority label?
• Have you added or updated tests?
• Is the documentation up to date?

Solution

• Add a sinsemilla_ prefix to sinsemilla tests. 09fe7f7
• Replace old link with a working one. 0e7a46f

Review

Anyone can review.

Reviewer Checklist

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• Does the PR scope match the ticket?
• Are there enough tests to make sure it works? Do the tests cover the PR motivation?
• Are all the PR blockers dealt with?
  PR blockers can be dealt with in new tickets or PRs.

And check the PR Author checklist is complete.

Follow Up Work

[teor2345]

Thanks!