message: Fix protoc support on Windows
diff: Function Get-ProtobufTag() {
  + $releases = 'https://github.com/protocolbuffers/protobuf/releases'
  if("$protobuf_tag" -eq "latest") {
  - $protobuf_tag = (Invoke-RestMethod https://api.github.com/repos/protocolbuffers/protobuf/releases).tag_name | Where-Object { $_ -match "v\d+.\d+.\d+$" } | Select-Object -First 1
  + $protobuf_tag = (Invoke-WebRequest -UseBasicParsing -Uri $releases/latest).BaseResponse.RequestMessage.RequestUri.Segments[-1]
  } else {
  try {
  - [net.httpWebRequest] $request = [net.webRequest]::create("https://github.com/protocolbuffers/protobuf/releases/tag/v$protobuf_tag")
  - $req.Method = "HEAD"
  + $protobuf_tag = $protobuf_tag -replace '^v', ''
  + [net.httpWebRequest] $request = [net.webRequest]::create("$releases/tag/v$protobuf_tag")
  + $request.Method = "HEAD"
  [net.httpWebResponse] $response = $request.getResponse()
  $response.Close()
  $protobuf_tag = "v$protobuf_tag"
  } catch {
  - $protobuf_tag = (Invoke-RestMethod https://api.github.com/repos/protocolbuffers/protobuf/releases).tag_name | Where-Object { $_ -match "v\d+.\d+.\d+$" } | Select-Object -First 1
  + $protobuf_tag = (Invoke-WebRequest -UseBasicParsing -Uri $releases/latest).BaseResponse.RequestMessage.RequestUri.Segments[-1]
  }
  }
  return $protobuf_tag
  