Bump nextdns to version 3.1.0

[bieniu]

Breaking change

Proposed change

I have recently noticed that the NextDNS API responds to requests with a delay or responds with a 500/503 status. This causes the entities to become unavailable. This PR fixes these problems.

It bumps nextdns to version 3.1.0 to:

• move HTTP request timeout to backend library
• use tenacity to retry the request when it fails

Changelog: bieniu/nextdns@3.0.0...3.1.0

Type of change

• Dependency upgrade
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• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
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