Enable hyperref in hw_preamble.tex

Change-Id: I08b715f44cc77e9375578c6d7984e0083c973865
diff --git a/quad9/hw_preamble.tex b/quad9/hw_preamble.tex
index 35160bc..dfa8f4c 100644
--- a/quad9/hw_preamble.tex
+++ b/quad9/hw_preamble.tex
@@ -6,7 +6,7 @@
 \usepackage{parskip}
 \usepackage[dvipsnames]{xcolor}
 \usepackage{tcolorbox}
-%\usepackage{hyperref}
+\usepackage{hyperref}
 \usepackage{geometry}
 \usepackage{physics}
 \usepackage{systeme,mathtools}