Update dependency FluentAssertions to 8.1.0

Author: renovate[bot]

tests/Markdown.ColorCode.UnitTests/Markdown.ColorCode.UnitTests.csproj

@@ -17,7 +17,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="FluentAssertions" Version="8.0.1" />
+    <PackageReference Include="FluentAssertions" Version="8.1.0" />
     <PackageReference Include="FluentAssertions.Analyzers" Version="0.34.1">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>