Bump Microsoft.OpenApi from 2.9.0 to 3.8.0

---
updated-dependencies:
- dependency-name: Microsoft.OpenApi
  dependency-version: 3.8.0
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: dotnet
...

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

Author: dependabot[bot]

Directory.Packages.props

@@ -13,8 +13,8 @@
          Microsoft.OpenApi 2.0.0. net9.0's Microsoft.AspNetCore.OpenApi 9.0.17 already depends on the
          unaffected 1.x line, so only override the net10.0 leg; remove once AspNetCore.OpenApi bumps its own
          floor past 2.7.5. -->
-    <MicrosoftOpenApiVersion>2.9.0</MicrosoftOpenApiVersion>
-    <MicrosoftOpenApiVersion Condition="'$(TargetFramework)' == 'net9.0'">1.6.17</MicrosoftOpenApiVersion>
+    <MicrosoftOpenApiVersion>3.8.0</MicrosoftOpenApiVersion>
+    <MicrosoftOpenApiVersion Condition="'$(TargetFramework)' == 'net9.0'">3.8.0</MicrosoftOpenApiVersion>
   </PropertyGroup>
   <ItemGroup>
     <PackageVersion Include="Aspire.Hosting.PostgreSQL" Version="$(AspireVersion)" />

samples/WebApi/WebApi.Tests/WebApi.Tests.csproj

@@ -12,6 +12,7 @@
 	</ItemGroup>
 
 	<ItemGroup>
+		<PackageReference Include="Microsoft.OpenApi" VersionOverride="3.8.0" />
 		<PackageReference Include="Testcontainers.PostgreSql" />
 		<PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" />
 		<PackageReference Include="Moq.AutoMock" />