Updated WordPress citation package

With the sad passing of Dr. Nick Higham, I remembered that he commented on one of my blog posts. However, when I tried to access the post, I received a critical WordPress error. It turns out that the papercite package is unsupported for modern WordPress. I therefore switched to using teachPress. While not exactly the same, especially in that it will simply repeat identical entries instead of combining them, it gets the job done. It also means that the correlation matrix correction post is visible again!