Remove no longer necessary line ending escape hack

It appears that with recent releases icalendar-rs fixed the escape
issues relating to line endings. As such, we no longer need the hack
that we put in place to work around the broken logic earlier. Remove it.

src/ser/backends/ical/task.rs

@@ -78,10 +78,6 @@ impl TryFrom<&Todo> for Task {
       .get_description()
       .unwrap_or("")
       .to_string()
-      // TODO: The first `replace` should not be necessary. It is needed right
-      //       now due to https://github.com/hoodie/icalendar-rs/issues/87,
-      //       but this should be fixed upstream.
-      .replace("\\n", "\n")
       .replace('\n', LINE_END_STR);
     let tags = todo
       .property_value(TAGS_PROPERTY)