mermaid v8.9.2 upgrade for gitlab v13.12.2

Intro

I'm using GitLab on Synology. Latest package of the GitLab there is 13.12.2. I'd like to render this simple mermaid flowchart:

flowchart TB
  A --> B
  B --> C

  subgraph B
    B1 -.-> B2  
  end

Problem to discuss

On my editor (vscode, with mermaid extension) it is working, but on wiki running on GitLab v13.12.2 I'm getting "error message: syntax error in graph" (see screenshots).

The issue (connected to GitLab v13.12.2):

  • flowchart can't render connection between node (or subgraph) to subgraph (A-->B, B-->C)
  • only node to node (also included inside subgraph) is working (e.g. A-->B1, B2-->C)

After short investigation I know this:

  • vscode mermaid extension uses mermaid v8.13.3
  • GitLab v13.12.2 uses mermaid v8.9.2
  • starting mermaid v8.11 is possible connect nodes to subgraph (see my post in mermaid issues).

result: it seems mermaid v8.9.2 can't render connection from/to subgraphs

Screenshot

Expand for screenshot Mermaid code:
mermaid-code

Mermaid render (v8.13.3 in vscode):
mermaid-8-13-3-preview

Mermaid render (v8.9.2 - wiki on gitlab 13.12.2):
mermaid-8-9-2-preview

Question / Possible fixes

Q1: From which version of GitLab is mermaid v8.11+ 'included'?

Q2: Is it possible upgrade only mermaid v8.9.2 for existing GitLab 13.12.2? (I'm limited about upgrade GitLab package, because Synology)