Bump Microsoft.AspNetCore.All

Bumps [Microsoft.AspNetCore.All](https://github.com/aspnet/AspNetCore) from 2.1.5 to 2.1.15.
- [Release notes](https://github.com/aspnet/AspNetCore/releases)
- [Changelog](https://github.com/dotnet/aspnetcore/blob/main/docs/ReleasePlanning.md)
- [Commits](dotnet/aspnetcore@2.1.5...v2.1.15)

---
updated-dependencies:
- dependency-name: Microsoft.AspNetCore.All
  dependency-type: direct:production
...

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Author: dependabot[bot]

IdentityServer4-Client-TestUser/ApiResource/ApiResource.csproj

@@ -13,7 +13,7 @@
 
   <ItemGroup>
     <PackageReference Include="IdentityServer4.AccessTokenValidation" Version="2.6.0" />
-    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.1.5" />
+    <PackageReference Include="Microsoft.AspNetCore.All" Version="2.1.15" />
     <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.1.5" />
   </ItemGroup>