Chore(deps): Bump TUnit from 1.2.3 to 1.3.15

---
updated-dependencies:
- dependency-name: TUnit
  dependency-version: 1.3.15
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Directory.Packages.props

@@ -18,6 +18,6 @@
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.14.0" />
     <PackageVersion Include="Microsoft.CodeAnalysis.Common" Version="4.14.0" />
     <PackageVersion Include="Moq" Version="4.20.72" />
-    <PackageVersion Include="TUnit" Version="1.2.3" />
+    <PackageVersion Include="TUnit" Version="1.3.15" />
   </ItemGroup>
 </Project>