[main <T] Fix neighbors.at_hop bug

[mpintaric55334]

Description

Please briefly explain the changes you made here.

Fixed a bug user wanted to fix. Now, neighbors.at_hop wont throw an exeption when there are no neighbors, instead ti will return nothing. @matea16 tagging you just in case you want to notify the user when this is merged.

Pull request type

• [x] Bugfix
• [ ] Algorithm/Module
• [ ] Feature
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes
• [ ] Other (please describe):

Related issues

Delete if this PR doesn't resolve any issues. Link the issue if it does. https://github.com/memgraph/mage/issues/374 ######################################

Reviewer checklist (the reviewer checks this part)

Module/Algorithm

• [ ] Core algorithm/module implementation
• [ ] Query module implementation
• [ ] Unit tests
• [ ] End-to-end tests
• [ ] Code documentation
• [ ] README short description
• [ ] Documentation on memgraph/docs
• [ ] Update GQLALchemy signatures in query builder using query module signature generator

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