Downgrading .NET SDK on Crank pipeline

[tonyredondo]

The crank pipeline has been failing since the new .NET 5 SDK 5.0.202 release.
This problem is happening also in other repos:
dotnet/sdk#16774

This PR downgrade the SDK version to the same one used by others pipelines.

Before PR:

Welcome to .NET 5.0!
---------------------
SDK Version: 5.0.202

Telemetry
---------
The .NET tools collect usage data in order to help us improve your experience. It is collected by Microsoft and shared with the community. You can opt-out of telemetry by setting the DOTNET_CLI_TELEMETRY_OPTOUT environment variable to '1' or 'true' using your favorite shell.

Read more about .NET CLI Tools telemetry: https://aka.ms/dotnet-cli-telemetry

----------------
Installed an ASP.NET Core HTTPS development certificate.
To trust the certificate run 'dotnet dev-certs https --trust' (Windows and macOS only).
Learn about HTTPS: https://aka.ms/dotnet-https
----------------
Write your first app: https://aka.ms/dotnet-hello-world
Find out what's new: https://aka.ms/dotnet-whats-new
Explore documentation: https://aka.ms/dotnet-docs
Report issues and find source on GitHub: https://github.com/dotnet/core
Use 'dotnet --help' to see available commands or visit: https://aka.ms/dotnet-cli
--------------------------------------------------------------------------------------
Microsoft (R) Build Engine version 16.9.0+57a23d249 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.

  Determining projects to restore...
##[error]src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj(0,0): Error NU1101: Unable to find package StyleCop.Analyzers. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
D:\a\1\s\src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj : error NU1101: Unable to find package StyleCop.Analyzers. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
##[error]src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj(0,0): Error NU1101: Unable to find package Microsoft.NETFramework.ReferenceAssemblies. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
D:\a\1\s\src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj : error NU1101: Unable to find package Microsoft.NETFramework.ReferenceAssemblies. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
##[error]src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj(0,0): Error NU1101: Unable to find package Microsoft.NETCore.App. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
D:\a\1\s\src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj : error NU1101: Unable to find package Microsoft.NETCore.App. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
  Failed to restore D:\a\1\s\src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj (in 1.14 sec).

Build FAILED.

D:\a\1\s\src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj : error NU1101: Unable to find package StyleCop.Analyzers. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
D:\a\1\s\src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj : error NU1101: Unable to find package Microsoft.NETFramework.ReferenceAssemblies. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
D:\a\1\s\src\Datadog.Trace.ClrProfiler.Managed.Loader\Datadog.Trace.ClrProfiler.Managed.Loader.csproj : error NU1101: Unable to find package Microsoft.NETCore.App. No packages exist with this id in source(s): Microsoft Visual Studio Offline Packages
    0 Warning(s)
    3 Error(s)

@DataDog/apm-dotnet