fix: handle css-like input entries correctly

[sjelfull]

This fixes instances where you have a CSS-like file as input, for example a SCSS file.

Example config:

import { defineConfig } from 'vite'

export default defineConfig({
    base: '/dist/',
    build: {
        outDir: 'html/dist',
        manifest: true,
        emptyOutDir: true,
        rollupOptions: {
            input: {
                style: './scss/style.scss'
            }
        }
    }
})

Before this change it would create a script tag but no link tags. Now it only creates a link tag and no script tag.