Switch to Node.js v20 before we can upgrade @polkadot dependencies #5933

Job	Run time
sanity-tests	4s
cargo audit	4m 23s
docker-build	26m 17s
sanity-test-cli	36s
Clippy	17m 29s
Rustfmt	23s
build-creditcoin-node	11m 38s
check	13m 57s
unit-test-cli	48s
unit-test-creditcoin	38m 51s
build-creditcoin-transaction-producer	17m 25s
javascript-format / creditcoin-js	23s
javascript-format / integration-tests	32s
javascript-lint / creditcoin-js	29s
javascript-typecheck / creditcoin-js	24s
javascript-format / scripts/js	31s
javascript-lint / integration-tests	35s
javascript-typecheck / integration-tests	32s
javascript-format / scripts/cc-cli	32s
javascript-lint / scripts/js	31s
javascript-typecheck / scripts/js	30s
javascript-lint / scripts/cc-cli	38s
javascript-typecheck / scripts/cc-cli	33s
benchmark	31m 11s
🐚 Shellcheck	6s
integration-test-loan-cycle	17m 13s
integration-test-cli	40m 57s
tools-creditcoin-transaction-producer	2m 21s
	3h 49m 49s

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