Update Expat to 2.7.3

Author: mdaines

packages/viz/CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+* Update Expat to 2.7.3.
+
 ## 3.18.0
 
 * Update Graphviz to 14.0.0.

packages/viz/backend/Dockerfile

@@ -2,7 +2,7 @@ FROM emscripten/emsdk:3.1.70 AS graphviz
 
 ENV PREFIX=/prefix
 
-ADD "https://github.com/libexpat/libexpat/releases/download/R_2_7_2/expat-2.7.2.tar.gz" ./expat.tar.gz
+ADD "https://github.com/libexpat/libexpat/releases/download/R_2_7_3/expat-2.7.3.tar.gz" ./expat.tar.gz
 
 RUN mkdir -p expat && tar -zxf ./expat.tar.gz --strip-components 1 --directory expat
 RUN cd expat && emconfigure ./configure \