Bump rxml to 0.13.1

rxml 0.13.0 changed the quoting style to make it consistent, so we have
to patch up all affected places where we match exact strings.

minidom/CHANGELOG.md

@@ -1,6 +1,7 @@
 Version NEXT:
   * Changes
     * Almost make the whole crate `no_std`, only `std::io` is still remaining.
+    * Update rxml dependency to 0.13.
 
 Version 0.16, released 2024-07-23:
   * Breaking