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
- 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] <support@github.com>

Author: dependabot[bot]

test/Microsoft.OpenApi.Hidi.Tests/Microsoft.OpenApi.Hidi.Tests.csproj

@@ -14,7 +14,7 @@
 
   <ItemGroup>
     <PackageReference Include="coverlet.msbuild" Version="6.0.4" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="xunit" Version="2.9.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" PrivateAssets="all" />

test/Microsoft.OpenApi.Readers.Tests/Microsoft.OpenApi.Readers.Tests.csproj

@@ -17,7 +17,7 @@
     <ItemGroup>
         <PackageReference Include="coverlet.collector" Version="6.0.4" PrivateAssets="all" />
         <PackageReference Include="coverlet.msbuild" Version="6.0.4" PrivateAssets="all" />
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
         <PackageReference Include="FluentAssertions" Version="7.2.0" />
         <PackageReference Include="system.text.json" Version="9.0.9" />
         <PackageReference Include="xunit" Version="2.9.3" />

test/Microsoft.OpenApi.Tests/Microsoft.OpenApi.Tests.csproj

@@ -11,7 +11,7 @@
     <PackageReference Include="coverlet.collector" Version="6.0.4" PrivateAssets="all" />
     <PackageReference Include="coverlet.msbuild" Version="6.0.4" PrivateAssets="all" />
     <PackageReference Include="FluentAssertions" Version="7.2.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.0.0" />
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="System.Text.Json" Version="9.0.9" />
     <PackageReference Include="Verify.Xunit" Version="30.11.0" />