Update FluentAssertions to version 6.2.0

Author: 0xced

tests/Serilog.Formatting.Log4Net.Tests.csproj

@@ -9,7 +9,7 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.msbuild" Version="3.1.0" PrivateAssets="all" />
-    <PackageReference Include="FluentAssertions" Version="6.1.0" />
+    <PackageReference Include="FluentAssertions" Version="6.2.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
     <PackageReference Include="PublicApiGenerator" Version="10.2.0" />
     <PackageReference Include="ReportGenerator" Version="4.8.13" />