Asset Browser: Increase size of search button a bit

Before this, the search button was quite small really, not much text would fit
into it. Increase the size a bit, but not too much to still make the layout
work in smaller area sizes.

release/scripts/startup/bl_ui/space_filebrowser.py

@@ -52,7 +52,9 @@ class FILEBROWSER_HT_header(Header):
             icon_only=True,
         )
 
-        layout.prop(params, "filter_search", text="", icon='VIEWZOOM')
+        sub = layout.row()
+        sub.ui_units_x = 8
+        sub.prop(params, "filter_search", text="", icon='VIEWZOOM')
 
         layout.popover(
             panel="ASSETBROWSER_PT_filter",