Bump nunit.engine from 3.17.0 to 3.18.1

Bumps [nunit.engine](https://github.com/nunit/nunit-console) from 3.17.0 to 3.18.1.
- [Release notes](https://github.com/nunit/nunit-console/releases)
- [Changelog](https://github.com/nunit/nunit-console/blob/main/CHANGES.txt)
- [Commits](nunit/nunit-console@3.17.0...3.18.1)

---
updated-dependencies:
- dependency-name: nunit.engine
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

src/Directory.Build.props

@@ -10,7 +10,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.507" PrivateAssets="all" />
+    <PackageReference Include="StyleCop.Analyzers" Version="1.2.0-beta.556" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>

src/NUnitTestAdapter/NUnit.TestAdapter.csproj

@@ -33,12 +33,12 @@
 
   <ItemGroup>
     <PackageReference Include="SourceLink.Create.CommandLine" Version="2.8.3" PrivateAssets="All" />
-    <PackageReference Include="nunit.engine" Version="3.17.0" />
+    <PackageReference Include="nunit.engine" Version="3.18.1" />
     <PackageReference Include="TestCentric.Metadata" Version="3.0.2" Aliases="TestCentric" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net462'">
-    <PackageReference Include="Microsoft.TestPlatform.ObjectModel" Version="11.0.0" PrivateAssets="All" />
+    <PackageReference Include="Microsoft.TestPlatform.ObjectModel" Version="15.0.0" PrivateAssets="All" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">