Theme colour meta tag doesn't update after inject

[cornae]

The theme colour meta tag doesn't update with page switches which can lead to a mismatch in colour between the browser bar (Safari MacOS, Safari iPad OS, Safari iOS, (Safari VisonOS?)).

Proposal: Update the theme colour meta tag (if present) in the same way as the contents of the title tag and other tags in the head section are updated by pat-inject.

<meta 
    name="theme-color" 
    content="#444444">