[Port] [6000.3] Set Editor Assemblies Compatibility Level to .NET Standard 2.1 for SRP_SmokeTest project

Author: svc-reach-platform-support

Tests/SRPTests/Projects/SRP_SmokeTest/ProjectSettings/ProjectSettings.asset

@@ -765,7 +765,7 @@ PlayerSettings:
   gcIncremental: 0
   gcWBarrierValidation: 0
   apiCompatibilityLevelPerPlatform: {}
-  editorAssembliesCompatibilityLevel: 1
+  editorAssembliesCompatibilityLevel: 3
   m_RenderingPath: 1
   m_MobileRenderingPath: 1
   metroPackageName: Template_3D