Editorial: remove a duplicate "in"

Author: linusg

fetch.bs

@@ -6642,7 +6642,7 @@ steps:
  <a for="byte sequence">length</a>.
 
  <li>
-  <p>If <var>action</var> is non-null, then run these steps in <a>in parallel</a>:
+  <p>If <var>action</var> is non-null, then run these steps <a>in parallel</a>:
 
   <ol>
    <li>