fix: update border-image-slice value when fill is toggled (fixes #63)

[webcrawls]

Description:

This PR updates the Border Image Generator tool, fixing a bug where the CSS code output is not updated when the fill checkbox is toggled.

Motivation:

Before this PR, the "CSS Code" section of the tool would not update the border-image-slice property when the fill value is toggled. This can lead to an inconsistency between given inputs and the resulting outputs. This PR fixes that by calling setOutputCSS inside the setBorderFill function, bringing it in-line with the behaviour of the setBorderSlice function.

Additional details:

• Can't think of any extra information, this PR is a single-line change so there shouldn't be many issues.

Related issues and pull requests:

• [Border-image generator] border-image-slice fill keyword not toggled in CSS output #63 references this problem, which is fixed and can be closed by this PR.
• I couldn't find any related pull requests.
• This PR doesn't depend on any other branches.

[pepelsbey]

Nice catch! Thank you :)