chore: Suppress obsolete warning in domain push tests (#237)

Add `#pragma warning disable 618` to the InitiatePush and InitiatePushValidationFail tests to silence compiler warnings about the obsolete InitiatePush API used in these test cases. This keeps test output clean while the legacy API is exercised.

Author: san983

src/dnsimple-test/Services/DomainsPushesTest.cs

@@ -25,6 +25,7 @@ public class DomainsPushesTest
         [TestCase(1010, "example.com", "https://api.sandbox.dnsimple.com/v2/1010/domains/example.com/pushes")]
         public void InitiatePush(long accountId, string domainIdentifier, string expectedUrl)
         {
+            #pragma warning disable 618
             var client = new MockDnsimpleClient(InitiatePushFixture);
             var push = client.Domains.InitiatePush(accountId, domainIdentifier,
                 "admin@target-account.test");
@@ -47,6 +48,7 @@ public void InitiatePush(long accountId, string domainIdentifier, string expecte
         [TestCase(null)]
         public void InitiatePushValidationFail(string email)
         {
+            #pragma warning disable 618
             var client = new MockDnsimpleClient(InitiatePushFixture);
 
             Assert.Throws(Is.TypeOf<ArgumentException>().And.Message.EqualTo("Email cannot be null or empty"),