phrase changelog entry 0.1.9 less ambiguously

Make changlog entry for version 0.1.9 less ambiguous by repeating the auxiliary verbs "has been" marking the past passive tense, so that it's clear that "the code that drives compilation for the CLI tool" is the object, not the subject of last part of the sentence, too.

CHANGELOG.md

@@ -107,7 +107,7 @@ Developer-facing improvements:
 - Tectonic is now more up-front about the fact that it requires Harfbuzz
   version 1.4 or higher.
 - Much of the code that drives compilation for the CLI tool has been moved
-  into the Tectonic library and made (more) reusable
+  into the Tectonic library and has been made (more) reusable
   ([#184](https://github.com/tectonic-typesetting/tectonic/pull/184)). Thanks
   to new contributor [@jneem](https://github.com/jneem) for doing this!