Sequential relative URLs with colons in the text not rendering correctly using the render_markdown templatetag

[drygdryg]

NetBox version

v3.1.9

Python version

3.10

Steps to Reproduce

1. Run NetBox shell and import the render_markdown templatetag:

$ /opt/netbox/venv/bin/python /opt/netbox/netbox/manage.py nbshell
### NetBox interactive shell (ubuntuserver)
### Python 3.10.2+ | Django 3.2.12 | NetBox 3.1.9
### lsmodels() will show available models. Use help(<model>) for more info.
>>> from utilities.templatetags.helpers import render_markdown

2. Try to render test case URLs:

>>> render_markdown('[TEST](/dcim/devices/1/)')
'<div class="rendered-markdown"><p><a href="/dcim/devices/1/">TEST</a></p></div>'  # Correct
>>> render_markdown('[TEST:](/dcim/devices/1/)')
'<div class="rendered-markdown"><p><a href="/dcim/devices/1/">TEST:</a></p></div>'  # Correct
>>> render_markdown('[TEST](/dcim/devices/1/) [TEST](/dcim/devices/1/)')
'<div class="rendered-markdown"><p><a href="/dcim/devices/1/">TEST</a> <a href="/dcim/devices/1/">TEST</a></p></div>'  # Correct
>>> render_markdown('[TEST](/dcim/devices/1/) [TEST:](/dcim/devices/1/)')
'<div class="rendered-markdown"><p>[TEST](](/dcim/devices/1/)</p></div>'  # Incorrect
>>> render_markdown('[TEST](https://netbox.site/dcim/devices/1/) [TEST:](https://netbox.site/dcim/devices/1/)')
'<div class="rendered-markdown"><p><a href="https://netbox.site/dcim/devices/1/">TEST</a> <a href="https://netbox.site/dcim/devices/1/">TEST:</a></p></div>'  # Correct

Expected Behavior

The string

[TEST](/dcim/devices/1/) [TEST:](/dcim/devices/1/)

should be rendered as

<div class="rendered-markdown"><p><a href="/dcim/devices/1/">TEST</a> <a href="/dcim/devices/1/">TEST:</a></p></div>

Observed Behavior

The string

[TEST](/dcim/devices/1/) [TEST:](/dcim/devices/1/)

was rendered as

<div class="rendered-markdown"><p>[TEST](](/dcim/devices/1/)</p></div>

[drygdryg]

I think there is a problem with the regular expression that captures colons in the URL text

netbox/netbox/utilities/templatetags/helpers.py

Line 52 in 6807db4

pattern = fr'\[([^\]]+)\]\((?!({schemes})).*:(.+)\)'

Possible the right change (just allow only characters allowed for URL scheme):

    pattern = fr'\[([^\]]+)\]\((?!({schemes}))[A-Za-z0-9\.+-]*:(.+)\)' 

Running the corrected regex in Regex101.com:

[github-actions]

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