Bump Microsoft.NET.Test.Sdk from 17.14.1 to 18.0.0

---
updated-dependencies:
- dependency-name: Microsoft.NET.Test.Sdk
  dependency-version: 18.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

test/GitHubLabelSync.Tests.csproj

@@ -5,7 +5,7 @@
 		<Nullable>enable</Nullable>
 	</PropertyGroup>
 	<ItemGroup>
-		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
 		<PackageReference Include="NSubstitute" Version="5.3.0" />
 		<PackageReference Include="xunit" Version="2.9.3" />
 		<PackageReference Include="xunit.runner.visualstudio" Version="3.1.5" />