(maint) Update dependency xunit.analyzers to 1.18.0 (#118)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

src/Diagramming.Tests/Diagramming.Tests.csproj

@@ -20,7 +20,7 @@
         <PackageReference Include="Moq" Version="4.20.72" />
         <PackageReference Include="Verify.Xunit" Version="28.6.0" />
         <PackageReference Include="xunit" Version="2.9.2"/>
-        <PackageReference Include="xunit.analyzers" Version="1.16.0" />
+        <PackageReference Include="xunit.analyzers" Version="1.18.0" />
         <PackageReference Include="xunit.runner.visualstudio" Version="3.0.0">
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>