Merge pull request #21893 from michaelnebel/cshar/updateroslyn

C#: Update Roslyn and other pinned depenencies.

Author: michaelnebel

csharp/extractor/Semmle.Extraction.CSharp/CodeAnalysisExtensions/SymbolExtensions.cs

@@ -664,7 +664,7 @@ public static bool IsCompilerGeneratedExtensionMethod(this IMethodSymbol method)
                 // Find the (possibly unbound) original extension method that maps to this implementation (if any).
                 var unboundDeclaration = extensions.SelectMany(e => e.GetMembers())
                     .OfType<IMethodSymbol>()
-                    .FirstOrDefault(m => SymbolEqualityComparer.Default.Equals(m.AssociatedExtensionImplementation, method.ConstructedFrom));
+                    .FirstOrDefault(m => SymbolEqualityComparer.Default.Equals(m.AssociatedExtensionImplementation?.ConstructedFrom, method.ConstructedFrom));
 
                 var isFullyConstructed = method.IsBoundGenericMethod();
                 if (isFullyConstructed && unboundDeclaration?.ContainingType is INamedTypeSymbol extensionType)

csharp/paket.dependencies

@@ -4,15 +4,15 @@ source https://api.nuget.org/v3/index.json
 # behave like nuget in choosing transitive dependency versions
 strategy: max
 
-nuget Basic.CompilerLog.Util 0.9.25
+nuget Basic.CompilerLog.Util 0.9.39
 nuget Mono.Posix.NETStandard
 nuget Newtonsoft.Json
 nuget NuGet.Versioning
 nuget xunit
 nuget xunit.runner.visualstudio
 nuget xunit.runner.utility
 nuget Microsoft.NET.Test.Sdk
-nuget Microsoft.CodeAnalysis.CSharp 5.0.0
-nuget Microsoft.CodeAnalysis 5.0.0
-nuget Microsoft.Build 18.0.2
+nuget Microsoft.CodeAnalysis.CSharp 5.3.0
+nuget Microsoft.CodeAnalysis 5.3.0
+nuget Microsoft.Build 18.6.3
 nuget Microsoft.VisualStudio.SolutionPersistence