Fix content.integration tests warnings (#17817)

Co-authored-by: metalgearsloth <31366439+metalgearsloth@users.noreply.github.com>

Content.IntegrationTests/Tests/Damageable/DamageSpecifierTest.cs

@@ -1,7 +1,6 @@
 using System.Collections.Generic;
 using Content.Shared.Damage;
 using Content.Shared.FixedPoint;
-using NUnit.Framework;
 
 namespace Content.IntegrationTests.Tests.Damageable;
 
@@ -23,9 +22,12 @@ public sealed class DamageSpecifierTest
         DamageSpecifier output4 = new() { DamageDict = _output4 };
         DamageSpecifier output5 = new() { DamageDict = _output5 };
 
-        Assert.That((-input1).Equals(output1));
-        Assert.That((input1 / 2).Equals(output2));
-        Assert.That((input1 * 2).Equals(output3));
+        Assert.Multiple(() =>
+        {
+            Assert.That((-input1).Equals(output1));
+            Assert.That((input1 / 2).Equals(output2));
+            Assert.That((input1 * 2).Equals(output3));
+        });
 
         var difference = (input1 - input2);
         Assert.That(difference.Equals(output4));