Fix year in release post
Fix year in release post

https://github.com/bitcoin-core/bitcoincore.org/commit/4a2f0fe269dcd1f73ac587a35e8f11a7e4e165eb#r64021846
bitcoin-core/bitcoincore.org,bitcoin-core/bitcoincore.org,bitcoin-core/bitcoincore.org,bitcoin-core/bitcoincore.org,bitcoin-core/bitcoincore.org,bitcoin-core/bitcoincore.org