Missing newlines in the codeblock

[zerodayz]

• [x] goldmark is fully compliant with the CommonMark. Before submitting issue, you must read CommonMark spec and confirm your output is different from CommonMark online demo.
  • [x] Extensions(Autolink without < >, Table, etc) are not part of CommonMark spec. You should confirm your output is different from other official renderers correspond with an extension.
• [x] goldmark is not dedicated for Hugo. If you are Hugo user and your issue was raised by your experience in Hugo, you should consider create issue at Hugo repository at first .
• [x] Before you make a feature request, you should consider implement the new feature as an extension by yourself . To keep goldmark itself simple, most new features should be implemented as an extension.

Please answer the following before submitting your issue:

1. What version of goldmark are you using? : v1.2.1
2. What version of Go are you using? : v1.14.3
3. What operating system and processor architecture are you using? : darwin
4. What did you do? :

    md := goldmark.New(
        goldmark.WithExtensions(
            extension.GFM,
            highlighting.NewHighlighting(
                highlighting.WithStyle("github"),
            ),
        ),
        goldmark.WithParserOptions(
            parser.WithAutoHeadingID(),
        ),
    )

    var buf bytes.Buffer

    md.Convert([]byte(s.Body), &buf)
    fmt.Println(buf.String())

\`\`\`bash
message
test
\`\`\`

5. What did you expect to see? :

For some reason it does not recognize the line breaks. With Firefox I can see two lines on one line.

<pre style="background-color:#fff">message
<span style="color:#0086b3">test</span>

6. What did you see instead? :

<pre style="background-color:#fff">message
<span style="color:#0086b3">test</span>

7. Did you confirm your output is different from CommonMark online demo or other official renderer correspond with an extension?:

Yes

8. (Feature request only): Why you can not implement it as an extension?:
   • You should avoid saying like "I'm not familiar with this project" "I'm not a Go programmer" as far as possible. This is an open source project and a library for Go programmers. I encourage you to strive to read source codes.
   • I absolutely welcome questions that are difficult even if you read the source codes.

[zerodayz]

Issue found in my own CSS. Sorry about that.

[zerodayz]

For anyone interested I had in pre element.

white-space: nowrap;