Treat warnings not as errors in manual test project (#2435)

* Treat all vulnerability severity levels not as errors.

* Disable treat warnings as errors for manual test project.

Author: timcassell

tests/BenchmarkDotNet.IntegrationTests.ManualRunning.MultipleFrameworks/BenchmarkDotNet.IntegrationTests.ManualRunning.MultipleFrameworks.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <AssemblyTitle>BenchmarkDotNet.IntegrationTests.ManualRunning.MultipleFrameworks</AssemblyTitle>
     <!-- We test the oldest frameworks supported by BDN (net461 and netcoreapp2.0), as well as newer versions of those frameworks. -->
-    <WarningsNotAsErrors>NU1904</WarningsNotAsErrors>
+    <TreatWarningsAsErrors>false</TreatWarningsAsErrors>
     <TargetFrameworks>net461;net48;netcoreapp2.0;net7.0</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <AssemblyName>BenchmarkDotNet.IntegrationTests.ManualRunning.MultipleFrameworks</AssemblyName>