ops: Bump NodeJS to v20.12.0 in start script

production/mempool-start-all

@@ -1,7 +1,7 @@
 #!/usr/bin/env zsh
 export NVM_DIR="$HOME/.nvm"
 source "$NVM_DIR/nvm.sh"
-nvm use v20.7.0
+nvm use v20.12.0
 
 # start all mempool backends that exist
 for site in mainnet mainnet-lightning testnet testnet-lightning signet signet-lightning bisq liquid liquidtestnet;do