Update emscripten Dockerfile to 3.1.19

scripts/docker/buildpack-deps/Dockerfile.emscripten

@@ -32,11 +32,15 @@
 # apparently this currently breaks due to conflicting compatibility headers.
 # Using $(em-config CACHE)/sysroot/usr seems to work, though, and still has cmake find the
 # dependencies automatically.
-FROM emscripten/emsdk:2.0.33 AS base
-LABEL version="11"
+FROM emscripten/emsdk:3.1.19 AS base
+LABEL version="12"
 
 ADD emscripten.jam /usr/src
 RUN set -ex; \
+\
+	apt-get update && \
+	apt-get install lz4 --no-install-recommends && \
+\
 	cd /usr/src; \
 	git clone https://github.com/Z3Prover/z3.git -b z3-4.8.17 --depth 1 ; \
 	cd z3; \
@@ -55,7 +59,7 @@ RUN set -ex; \
 	make ; make install; \
 	rm -r /usr/src/z3; \
 	cd /usr/src; \
-
+\
 	wget -q 'https://boostorg.jfrog.io/artifactory/main/release/1.75.0/source/boost_1_75_0.tar.bz2' -O boost.tar.bz2; \
 	test "$(sha256sum boost.tar.bz2)" = "953db31e016db7bb207f11432bef7df100516eeb746843fa0486a222e3fd49cb  boost.tar.bz2"; \
 	tar -xf boost.tar.bz2; \