Update to protobuf 1.27.0 (#1973)

Motivation:

SwiftProtobuf just released a 1.27.0 containing a few years worth of
changes and fixes.

Modifications:

- Update min version
- Fix test
- Regenerate protos

Result:

Protobuf is more up-to-date

Tests/GRPCProtobufCodeGenTests/ProtobufCodeGenParserTests.swift

@@ -348,7 +348,7 @@ extension Google_Protobuf_FileDescriptorProto {
       $0.name = "helloworld.proto"
       $0.package = "helloworld"
       $0.dependency = ["same-module.proto", "different-module.proto"]
-      $0.publicDependency = [1, 2]
+      $0.publicDependency = [0, 1]
       $0.messageType = [requestType, responseType]
       $0.service = [service]
       $0.sourceCodeInfo = Google_Protobuf_SourceCodeInfo.with {