Bump Google.Protobuf from 3.2.0 to 3.15.0 in /src/DotNetty.Codecs.Protobuf#1

dependabot[bot] wants to merge 1 commit intomastercdy816/DotNettyCore3:masterfrom

dependabot/nuget/src/DotNetty.Codecs.Protobuf/Google.Protobuf-3.15.0cdy816/DotNettyCore3:dependabot/nuget/src/DotNetty.Codecs.Protobuf/Google.Protobuf-3.15.0Copy head branch name to clipboard