Space missing before links inside <b> tag

Steps to reproduce:
```py
>>> import html2text
>>> html2text.html2text('This is a link right here')
'**This is[a link](https://example.com/) right here**\n\n'
```

Notice the space between the word "is" and the link is missing in the output, but is present in the input.

Tested and this issue is present on master. My python version is 3.8.10 on linux.