update to DiffEngine 15.5.5

Author: SimonCropp

src/Directory.Build.props

@@ -2,7 +2,7 @@
 <Project>
   <PropertyGroup>
     <NoWarn>CA1822;CS1591;CS0649;xUnit1026;xUnit1013;CS1573;VerifyTestsProjectDir;VerifySetParameters;PolyFillTargetsForNuget</NoWarn>
-    <Version>28.3.0</Version>
+    <Version>28.3.1</Version>
     <ImplicitUsings>enable</ImplicitUsings>
     <LangVersion>preview</LangVersion>
     <AssemblyVersion>1.0.0</AssemblyVersion>

src/Directory.Packages.props

@@ -7,7 +7,7 @@
     <PackageVersion Include="Argon" Version="0.25.0" />
     <PackageVersion Include="Argon.FSharp" Version="0.25.0" />
     <PackageVersion Include="BenchmarkDotNet" Version="0.14.0" />
-    <PackageVersion Include="DiffEngine" Version="15.5.4" />
+    <PackageVersion Include="DiffEngine" Version="15.5.5" />
     <PackageVersion Include="Expecto" Version="10.2.1" />
     <PackageVersion Include="Fixie" Version="4.0.0" />
     <PackageVersion Include="Fixie.TestAdapter" Version="4.0.0" />