Bump TUnit from 1.6.15 to 1.6.20

---
updated-dependencies:
- dependency-name: TUnit
  dependency-version: 1.6.20
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

EliteAPI.Tests/EliteAPI.Tests.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="TUnit" Version="1.6.15" />
+    <PackageReference Include="TUnit" Version="1.6.20" />
     <PackageReference Include="FluentAssertions" Version="8.8.0" />
   </ItemGroup>