fix xunit compiler warnings for integration tests

Author: christianspecht

src/ScmBackup.Tests.Integration/DirectoryHelperTests.cs

@@ -23,7 +23,7 @@ public void DirectoryWithSuffixIsCreated()
 
             Assert.False(string.IsNullOrWhiteSpace(result));
             Assert.True(Directory.Exists(result));
-            Assert.True(result.EndsWith(suffix));
+            Assert.EndsWith(suffix, result);
         }
 
         [Fact]

src/ScmBackup.Tests.Integration/HosterFactoryTests.cs

@@ -20,7 +20,7 @@ public HosterFactoryTests()
         [Fact]
         public void NewHosterIsAdded()
         {
-            Assert.Equal(1, sut.Count);
+            Assert.Single(sut);
         }
 
         [Fact]

src/ScmBackup.Tests.Integration/ScmFactoryTests.cs

@@ -23,7 +23,7 @@ public ScmFactoryTests()
         [Fact]
         public void NewScmIsAdded()
         {
-            Assert.Equal(1, sut.Count);
+            Assert.Single(sut);
         }
 
         [Fact]