docker: Update litecoin to non-vulnerable version

This was forgotten in ElementsProject#2021

Signed-off-by: Christian Decker <@cdecker>
Reported-by: Romano <@romanornr>

Dockerfile

@@ -38,10 +38,10 @@ RUN mkdir /opt/bitcoin && cd /opt/bitcoin \
     && tar -xzvf $BITCOIN_TARBALL $BD/bitcoin-cli --strip-components=1 \
     && rm $BITCOIN_TARBALL
 
-ENV LITECOIN_VERSION 0.14.2
-ENV LITECOIN_URL https://download.litecoin.org/litecoin-0.14.2/linux/litecoin-0.14.2-x86_64-linux-gnu.tar.gz
-ENV LITECOIN_SHA256 05f409ee57ce83124f2463a3277dc8d46fca18637052d1021130e4deaca07b3c
-ENV LITECOIN_ASC_URL https://download.litecoin.org/litecoin-0.14.2/linux/litecoin-0.14.2-linux-signatures.asc
+ENV LITECOIN_VERSION 0.16.3
+ENV LITECOIN_URL https://download.litecoin.org/litecoin-0.16.3/linux/litecoin-0.16.3-x86_64-linux-gnu.tar.gz
+ENV LITECOIN_SHA256 686d99d1746528648c2c54a1363d046436fd172beadaceea80bdc93043805994
+ENV LITECOIN_ASC_URL https://download.litecoin.org/litecoin-0.16.3/linux/litecoin-0.16.3-linux-signatures.asc
 ENV LITECOIN_PGP_KEY FE3348877809386C
 
 # install litecoin binaries