Bump Xamarin.MacDev.

[mandel-macaque]

Bump the dependency to be able to land PR: #6797

Commits:

• Add entitlement keys for Hardened Runtime (Xamarin.Mac Extension Support #44) dotnet/macios-devtools@47643c7
• Add new Xcode 11 entitlements dotnet/macios-devtools@ba3489f
• Merge pull request [Fix] Fix bug 24078 by adding the required attrs to generate the events. #47 from xamarin/xcode-11-entitlement-keys dotnet/macios-devtools@009ef79
• Add UserManagement entitlement key dotnet/macios-devtools@870c4d6
• Add System Extension entitlement dotnet/macios-devtools@21024aa
• [vsts-935384] Remove SupportsSGenConcurrentGCExperimental from SDKs dotnet/macios-devtools@27621cb
• Merge pull request [AudioToolbox] Add missing MusicSequence.SetUserCallback method #48 from xamarin/olegoid/vsts-935384 dotnet/macios-devtools@35f72d1
• [vsts-904676] Add multiple screens manifest keys dotnet/macios-devtools@793a3c7
• Merge pull request [runtime] Re-enable the gc pump by default for debug simulator/mac builds. #50 from xamarin/vsts-904676 dotnet/macios-devtools@fbedfba
• [vsts-938452] Add altool feature support dotnet/macios-devtools@0ef44e6
• Merge pull request [mtouch] Look where XS 6.1+ has installed mlaunch. Fixes part of #41083 #51 from xamarin/olegoid/altool-feature-support dotnet/macios-devtools@f9216e8
• Add support for Apple Development certificates dotnet/macios-devtools@ab3ba56
• Fix authenticode certs dotnet/macios-devtools@644b7ed
• Merge pull request Use a separate mono clone for watchOS. #56 from xamarin/dev/soch/fix_certs dotnet/macios-devtools@188fc34
• Merge pull request Update README.md #54 from wjk/apple-development dotnet/macios-devtools@445d943

Full diff: dotnet/macios-devtools@85e6023...445d943

[monojenkins]

Build success
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✅ API Diff (from PR only) (no change)
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