fix(proxies): return None for unservable queries and repair live providers

Basic, NordVPN, Windscribe, Gluetun and Hola no longer raise on a query they cannot serve. Hola parses stdout only and reports a ban; NordVPN cities use the API filter; uk maps to gb.

tests/core/test_basic_proxy.py

@@ -0,0 +1,30 @@
+"""Unit tests for the Basic proxy provider: a query it cannot serve returns None so a bare query moves on."""
+
+from __future__ import annotations
+
+import pytest
+
+from unshackle.core.proxies import Basic
+
+pytestmark = pytest.mark.unit
+
+
+@pytest.fixture
+def basic() -> Basic:
+    return Basic(us=["http://one.example:8080", "http://two.example:8080"], gb="http://gb.example:8080")
+
+
+@pytest.mark.parametrize(
+    ("query", "expected"), [("us1", "http://one.example:8080"), ("US2", "http://two.example:8080")]
+)
+def test_numbered_entry(basic: Basic, query: str, expected: str) -> None:
+    assert basic.get_proxy(query) == expected
+
+
+def test_single_entry_region(basic: Basic) -> None:
+    assert basic.get_proxy("gb") == "http://gb.example:8080"
+
+
+@pytest.mark.parametrize("query", ["us-bos", "yul", "us:seattle", "us150", "us0", "ca"])
+def test_query_it_cannot_serve_returns_none(basic: Basic, query: str) -> None:
+    assert basic.get_proxy(query) is None