[build] Bump to Mono with MSBuild 16.10

We've been seeing a NuGet restore issue when running prepare on a macOS
system with .NET 6 Preview 4 (or greater) installed:

    Restoring packages for /Users/peter/source/java.interop/tools/logcat-parse/logcat-parse.csproj...
    NU1202: Package Mono.CSharp 4.0.0.143 is not compatible with net6.0 (.NETCoreApp,Version=v6.0). Package Mono.CSharp 4.0.0.143 supports: net45 (.NETFramework,Version=v4.5)
    ...
    Errors in /Users/peter/source/java.interop/tools/logcat-parse/logcat-parse.csproj
        NU1202: Package Mono.CSharp 4.0.0.143 is not compatible with net6.0 (.NETCoreApp,Version=v6.0). Package Mono.CSharp 4.0.0.143 supports: net45 (.NETFramework,Version=v4.5)

I have encountered other issues with .NET 6 Preview 4 and greater when
building some projects targeting net6.0:

    Version 'x' of the .NET Core SDK requires at least version 16.10.0 of MSBuild. The current available version of MSBuild is 16.9.0. Change the .NET Core SDK specified in global.json to an older version that requires the MSBuild version currently available.

These issues should be addressed by using MSBuild 16.10 on macOS.

Author: pjcollins

Configuration.props

@@ -93,8 +93,8 @@
     <AndroidSupportedTargetJitAbis Condition=" '$(AndroidSupportedTargetJitAbis)' == '' ">armeabi-v7a:arm64-v8a:x86:x86_64</AndroidSupportedTargetJitAbis>
     <JavaInteropSourceDirectory Condition=" '$(JavaInteropSourceDirectory)' == '' ">$(MSBuildThisFileDirectory)external\Java.Interop</JavaInteropSourceDirectory>
     <MonoSourceDirectory>$(MSBuildThisFileDirectory)external\mono</MonoSourceDirectory>
-    <MonoDarwinPackageUrl>https://xamjenkinsartifact.azureedge.net/build-package-osx-mono/2020-02/144/b4a385816ed4f1398d0184c38f19f560e868fd80/MonoFramework-MDK-6.12.0.137.macos10.xamarin.universal.pkg</MonoDarwinPackageUrl>
-    <MonoRequiredMinimumVersion Condition=" '$(MonoRequiredMinimumVersion)' == '' ">6.12.0.137</MonoRequiredMinimumVersion>
+    <MonoDarwinPackageUrl>https://xamjenkinsartifact.azureedge.net/build-package-osx-mono/2020-02/151/c633fe923832f0c3db3c4e6aa98e5592bf5a06e7/MonoFramework-MDK-6.12.0.145.macos10.xamarin.universal.pkg</MonoDarwinPackageUrl>
+    <MonoRequiredMinimumVersion Condition=" '$(MonoRequiredMinimumVersion)' == '' ">6.12.0.145</MonoRequiredMinimumVersion>
     <MonoRequiredMaximumVersion Condition=" '$(MonoRequiredMaximumVersion)' == '' ">6.12.99</MonoRequiredMaximumVersion>
     <IgnoreMaxMonoVersion Condition=" '$(IgnoreMaxMonoVersion)' == '' And '$(RunningOnCI)' == 'true' ">False</IgnoreMaxMonoVersion>
     <IgnoreMaxMonoVersion Condition=" '$(IgnoreMaxMonoVersion)' == '' ">True</IgnoreMaxMonoVersion>