Send an empty datagram to estabilish connection to udp servers

[Williangalvani]

PyGPSClient Pull Request Template

Description

This makes us send an empty datagram when connecting to an UDP server. This is required as UDP is a connectionless protocol, so the server can only start sending us data once we send it something to let it know we exist.

Fixes # (issue)

Testing

Please test all changes, however trivial, against the supplied pytest suite tests/test_*.py. Please describe any test cases you have amended or added to this suite to maintain >= 99% code coverage.

• [x] Tested connecting to an M9N unit using bridges.

Checklist:

• [x] I agree to abide by the code of conduct (see CODE_OF_CONDUCT.md).
• [x] My code follows the style guidelines of this project (see CONTRIBUTING.MD).
• [x] I have performed a self-review of my own code.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [ ] I have made corresponding changes to the documentation.
• [ ] (if appropriate) I have added test cases to the tests/test_*.py unittest suite to maintain test coverage.
• [ ] I have tested my code against the full tests/test_*.py unittest suite.
• [ ] My changes generate no new warnings.
• [ ] Any dependent changes have been merged and published in downstream modules.
• [x] I have signed my commits.
• [x] I understand and acknowledge that the code will be published under a BSD 3-Clause license.