paket: fix build by requiring new MSBuild.StructuredLogger

AppVeyor was failing[1] with (which seemed to be same issue as
this one: [2]):

Script reported an error:
-> BuildFailedException: Target 'Build' failed.
-> One or more errors occurred. (Unsupported log file format. Latest supported version is 9, the log file has version 13.)
-> NotSupportedException: Unsupported log file format. Latest supported version is 9, the log file has version 13

[1] https://ci.appveyor.com/project/sergey-tihon/fsharpx-collections/builds/40656359
[2] fsprojects/FAKE#2595

paket.lock

@@ -136,7 +136,7 @@ NUGET
       Fake.Core.Trace (>= 5.20.3) - restriction: >= netstandard2.0
       Fake.IO.FileSystem (>= 5.20.3) - restriction: >= netstandard2.0
       FSharp.Core (>= 4.7.2) - restriction: >= netstandard2.0
-      MSBuild.StructuredLogger (>= 2.1.176) - restriction: >= netstandard2.0
+      MSBuild.StructuredLogger (>= 2.1.545) - restriction: >= netstandard2.0
     Fake.DotNet.NuGet (5.20.3) - restriction: >= netstandard2.0
       Fake.Core.Environment (>= 5.20.3) - restriction: >= netstandard2.0
       Fake.Core.Process (>= 5.20.3) - restriction: >= netstandard2.0
@@ -240,7 +240,7 @@ NUGET
     Microsoft.Win32.SystemEvents (5.0) - restriction: >= netcoreapp3.0
       Microsoft.NETCore.Platforms (>= 5.0) - restriction: >= netcoreapp2.0
     Mono.Posix.NETStandard (1.0) - restriction: >= netstandard2.0
-    MSBuild.StructuredLogger (2.1.215) - restriction: >= netstandard2.0
+    MSBuild.StructuredLogger (2.1.545) - restriction: >= netstandard2.0
       Microsoft.Build (>= 16.4) - restriction: >= netstandard2.0
       Microsoft.Build.Framework (>= 16.4) - restriction: >= netstandard2.0
       Microsoft.Build.Tasks.Core (>= 16.4) - restriction: >= netstandard2.0