Internal anchor links to content tabs aren't valid

[hazzuk]

Extension version: 0.1.0

Expected behavior

Creating an internal link to a page's content tab anchor link is valid.

Actual behavior

The extension wrongly gives an error: Invalid internal anchor.

Even though the link does still function when used.

Describe the issue

Zensical automatically adds an anchor link to each content tab. However, the extension neither suggests or accepts including an anchor link to content tabs.

# Index.md

[link](page2.md#tab2) <!-- extension errors this link -->

# Page2.md

=== "tab1"

    One.

=== "tab2"

    Two.

(The PyMdown Tabbed option combine_header_slug = true makes no difference)