fixed add/rem author funtionality for bs5 and converted to svg icons away from fontawesome

templates/subbooks_for_book.html

@@ -17,7 +17,10 @@
 					success: function(data){
 						$('#sub_book_content').html(data); } 
 					} ); return false;">
-					<i class="fas fa-angle-double-up" style="font-size:10px"></i></button>
+					<svg width="12" height="12" fill="currentColor">
+						<use xlink:href="{{url_for('static', filename='icons.svg')}}#caret-up-fill"/>
+					</svg>
+					</button>
 			{% set state="" %}
 			{% if loop.index == sub_books|length %}
 				{% set state="disabled" %}
@@ -29,7 +32,10 @@
 					success: function(data){
 						$('#sub_book_content').html(data); } 
 					} ); return false;">
-				<i class="fas fa-angle-double-down" style="font-size:10px"></i></button>
+				<svg width="12" height="12" fill="currentColor">
+					<use xlink:href="{{url_for('static', filename='icons.svg')}}#caret-down-fill"/>
+				</svg>
+				</button>
 			<a href="/book/{{book.sub_book_id}}">{{book.title}}</a>
 		</td>
 		<td>{{book.rating}}</td><td>{{book.author}}</td><td>{{book.year_published}}</td>