Incorrect escaping of characters in code blocks.

### Steps to reproduce

Post a message to chat in code block starting with three `.

Example:

```rust
>k::Label
```

### Outcome

#### What did you expect?

Element properly shows code block:

```rust
>k::Label
```

#### What happened instead?

Element turns the above code to:

```
>k::Label
```

### Operating system

Linux

### Application version

1.12.7

### How did you install the app?

via deb repository (element-desktop package)

### Homeserver

_No response_

### Will you send logs?

No