Add xmlstarlet

Author: blankzero0

Dockerfile

@@ -1,3 +1,7 @@
 FROM dart:3.6.1
 
 RUN dart pub global activate junitreport 2.0.2
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  xmlstarlet \
+  && rm -rf /var/lib/apt/lists/*