[Shared.Tests] Replace .NET 6 target with .NET 8 (open-telemetry#2182)

Author: joegoldman2

src/Shared/RequestDataHelper.cs

@@ -3,7 +3,7 @@
 
 #nullable enable
 
-#if NET8_0_OR_GREATER
+#if NET
 using System.Collections.Frozen;
 #endif
 using System.Diagnostics;
@@ -21,7 +21,7 @@ internal sealed class RequestDataHelper
 
     private static readonly char[] SplitChars = new[] { ',' };
 
-#if NET8_0_OR_GREATER
+#if NET
     private readonly FrozenDictionary<string, string> knownHttpMethods;
 #else
     private readonly Dictionary<string, string> knownHttpMethods;
@@ -46,7 +46,7 @@ public RequestDataHelper(bool configureByHttpKnownMethodsEnvironmentalVariable)
                 ["CONNECT"] = "CONNECT",
             };
 
-#if NET8_0_OR_GREATER
+#if NET
         this.knownHttpMethods = knownMethodSet.ToFrozenDictionary(StringComparer.OrdinalIgnoreCase);
 #else
         this.knownHttpMethods = knownMethodSet;

test/OpenTelemetry.Contrib.Shared.Tests/OpenTelemetry.Contrib.Shared.Tests.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <!-- OmniSharp/VS Code requires TargetFrameworks to be in descending order for IntelliSense and analysis. -->
-    <TargetFrameworks>$(SupportedNetTargets)</TargetFrameworks>
+    <TargetFrameworks>$(SupportedNetTargetsWithoutNet6)</TargetFrameworks>
     <TargetFrameworks Condition="$(OS) == 'Windows_NT'">$(TargetFrameworks);$(NetFrameworkMinimumSupportedVersion)</TargetFrameworks>
   </PropertyGroup>