Bump FluentAssertions from 7.0.0 to 8.6.0

---
updated-dependencies:
- dependency-name: FluentAssertions
  dependency-version: 8.6.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tests/DynamoDBGenerator.SourceGenerator.Tests/DynamoDBGenerator.SourceGenerator.Tests.csproj

@@ -11,7 +11,7 @@
 
     <ItemGroup>
         <PackageReference Include="AutoFixture" Version="5.0.0-preview0012" />
-        <PackageReference Include="FluentAssertions" Version="7.0.0"/>
+        <PackageReference Include="FluentAssertions" Version="8.6.0"/>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
         <PackageReference Include="xunit.runner.visualstudio" Version="3.1.2">
           <PrivateAssets>all</PrivateAssets>