Fix warnings in MinDateVersionFilter and shaVersionFilterTests

Author: HHobeck

src/GitVersion.Core.Tests/VersionCalculation/MinDateVersionFilterTests.cs

@@ -12,7 +12,7 @@ public void VerifyNullGuard()
         var dummy = DateTimeOffset.UtcNow.AddSeconds(1.0);
         var sut = new MinDateVersionFilter(dummy);
 
-        Should.Throw<ArgumentNullException>(() => sut.Exclude(null, out _));
+        Should.Throw<ArgumentNullException>(() => sut.Exclude(null!, out _));
     }
 
     [Test]

src/GitVersion.Core.Tests/VersionCalculation/ShaVersionFilterTests.cs

@@ -7,12 +7,12 @@ namespace GitVersion.Core.Tests;
 public class ShaVersionFilterTests : TestBase
 {
     [Test]
-    public void VerifyNullGuard2()
+    public void VerifyNullGuard()
     {
         var commit = GitToolsTestingExtensions.CreateMockCommit();
         var sut = new ShaVersionFilter(new[] { commit.Sha });
 
-        Should.Throw<ArgumentNullException>(() => sut.Exclude(null, out _));
+        Should.Throw<ArgumentNullException>(() => sut.Exclude(null!, out _));
     }
 
     [Test]