upgrade bitcoind to bitcoin core 0.21.0

docker/my-dojo/bitcoin/Dockerfile

@@ -5,10 +5,10 @@ FROM    debian:buster
 # INSTALL BITCOIN
 #################################################################
 ENV     BITCOIN_HOME        /home/bitcoin
-ENV     BITCOIN_VERSION     0.20.1
-ENV     BITCOIN_URL         https://bitcoincore.org/bin/bitcoin-core-0.20.1/bitcoin-0.20.1-x86_64-linux-gnu.tar.gz
-ENV     BITCOIN_SHA256      376194f06596ecfa40331167c39bc70c355f960280bd2a645fdbf18f66527397
-ENV     BITCOIN_ASC_URL     https://bitcoincore.org/bin/bitcoin-core-0.20.1/SHA256SUMS.asc
+ENV     BITCOIN_VERSION     0.21.0
+ENV     BITCOIN_URL         https://bitcoincore.org/bin/bitcoin-core-0.21.0/bitcoin-0.21.0-x86_64-linux-gnu.tar.gz
+ENV     BITCOIN_SHA256      da7766775e3f9c98d7a9145429f2be8297c2672fe5b118fd3dc2411fb48e0032
+ENV     BITCOIN_ASC_URL     https://bitcoincore.org/bin/bitcoin-core-0.21.0/SHA256SUMS.asc
 ENV     BITCOIN_PGP_KS_URI  hkp://keyserver.ubuntu.com:80
 ENV     BITCOIN_PGP_KEY     01EA5486DE18A882D4C2684590C8019E36C2E964