fix: bump oai version

Author: MaggieKimani1

src/Microsoft.OpenApi.OData.Reader/Microsoft.OpenAPI.OData.Reader.csproj

@@ -29,7 +29,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Microsoft.OData.Edm" Version="8.2.3" />
-    <PackageReference Include="Microsoft.OpenApi" Version="2.0.0-preview.14" />
+    <PackageReference Include="Microsoft.OpenApi" Version="2.0.0-preview.15" />
 	<None Include="..\..\README.md" Pack="true" PackagePath="\" />
 	<PackageReference Include="Microsoft.VisualStudio.Threading.Analyzers" Version="17.13.61">
 	  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

test/Microsoft.OpenAPI.OData.Reader.Tests/Microsoft.OpenAPI.OData.Reader.Tests.csproj

@@ -88,7 +88,7 @@
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
       <PrivateAssets>all</PrivateAssets>
     </PackageReference>
-    <PackageReference Include="Microsoft.OpenApi" Version="2.0.0-preview.14" />
+    <PackageReference Include="Microsoft.OpenApi" Version="2.0.0-preview.15" />
     <PackageReference Include="moq" Version="4.20.72" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.13.0" />
     <PackageReference Include="xunit" Version="2.9.3" />