Use example.com in single IP test

test.com now has 2 IPs so the test was failing, instead use example.com
which still has 1 IP.

Tests/KronosTests/DNSResolverTests.swift

@@ -5,7 +5,7 @@ final class DNSResolverTests: XCTestCase {
 
     func testResolveOneIP() {
         let expectation = self.expectation(description: "Query host's DNS for a single IP")
-        DNSResolver.resolve(host: "test.com") { addresses in
+        DNSResolver.resolve(host: "example.com") { addresses in
             XCTAssertEqual(addresses.count, 1)
             expectation.fulfill()
         }