fix: better host detection and cerbot only on valid hosts

tests/test_strings.py

@@ -0,0 +1,22 @@
+import parameterized
+
+from stapler.strings import sanitize_string, valid_host
+
+from . import BaseTestCase
+
+
+class TestStrings(BaseTestCase):
+    def test_sanitize(self) -> None:
+        self.assertEqual("??A??", sanitize_string("\n\tA\x00\x99"))
+
+    @parameterized.parameterized.expand(
+        [("example.com"), ("test-test.com"), ("subdomain.example.com")]
+    )
+    def test_valid_host(self, host: str) -> None:
+        self.assertTrue(valid_host(host), host)
+
+    @parameterized.parameterized.expand(
+        [("example.c"), ("localhost"), ("127.0.0.1"), ("test..com"), ("www-.test.com")]
+    )
+    def test_invalid_host(self, host: str) -> None:
+        self.assertFalse(valid_host(host), host)