fix: Adds curl to docker container builds for health checks.

docker/Dockerfile

@@ -65,6 +65,7 @@ RUN export DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true \
 # If your app or its dependencies import FoundationXML, also install `libxml2`.
       # libxml2 \
       sqlite3 \
+      curl \
     && rm -r /var/lib/apt/lists/*
 
 # Create a vapor user and group with /app as its home directory