Replace Understrap post nav font-awesome reference with inline Bootstrap Icons SVGs

understrap-post-nav.php

<?php
/**
 * Display navigation to next/previous post when applicable.
 */
function understrap_post_nav() {
	// Don't print empty markup if there's nowhere to navigate.
	$previous = ( is_attachment() ) ? get_post( get_post()->post_parent ) : get_adjacent_post( false, '', true );
	$next     = get_adjacent_post( false, '', false );
	if ( ! $next && ! $previous ) {
		return;
	}
	?>
	<nav class="container navigation post-navigation">
		<h2 class="screen-reader-text"><?php esc_html_e( 'Post navigation', 'understrap' ); ?></h2>
		<div class="d-flex nav-links justify-content-between">
			<?php
			if ( get_previous_post_link() ) {
				previous_post_link( '<span class="nav-previous">%link</span>', _x( '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-chevron-left" viewBox="0 0 16 16"><path fill-rule="evenodd" d="M11.354 1.646a.5.5 0 0 1 0 .708L5.707 8l5.647 5.646a.5.5 0 0 1-.708.708l-6-6a.5.5 0 0 1 0-.708l6-6a.5.5 0 0 1 .708 0z"/></svg>&nbsp;%title', 'Previous post link', 'understrap' ) );
			}
			if ( get_next_post_link() ) {
				next_post_link( '<span class="nav-next">%link</span>', _x( '%title&nbsp;<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-chevron-right" viewBox="0 0 16 16"><path fill-rule="evenodd" d="M4.646 1.646a.5.5 0 0 1 .708 0l6 6a.5.5 0 0 1 0 .708l-6 6a.5.5 0 0 1-.708-.708L10.293 8 4.646 2.354a.5.5 0 0 1 0-.708z"/></svg>', 'Next post link', 'understrap' ) );
			}
			?>
		</div><!-- .nav-links -->
	</nav><!-- .navigation -->
	<?php
}