Bump src/submodules/MessagePack-CSharp from `66ff408` to `6caf299`#3

dependabot[bot] wants to merge 1 commit intorelease/3.1ladeak/aspnetcore:release/3.1from

dependabot/submodules/release/3.1/src/submodules/MessagePack-CSharp-6caf299ladeak/aspnetcore:dependabot/submodules/release/3.1/src/submodules/MessagePack-CSharp-6caf299Copy head branch name to clipboard