completion(fish): add back ; as line endings in fish script

[peterdragun]

Adding back line ending which were removed in bcd3faa

• fixes Fish autocomplete stopped working on 8.1.4 #2567

Checklist:

• Add tests that demonstrate the correct behavior of the change. Tests should fail without the change.
• Add or update relevant docs, in the docs folder and in code.
• Add an entry in CHANGES.rst summarizing the change and linking to the issue.
• Add .. versionchanged:: entries in any relevant code docs.
• Run pre-commit hooks and fix any issues.
• Run pytest and tox, no tests failed.