feat(consensus): Isthmus Network Upgrade Txs #1333

Job	Run time
cfg-check	22s
clippy	26s
docs	21s
doctest	28s
examples	11s
feature-checks	36s
feature-powerset	1m 15s
fmt	14s
no-std	19s
test stable --no-default-features	39s
wasm-unknown	19s
wasm-wasi	19s
test stable	38s
test stable --all-features	1m 5s
test nightly --no-default-features	36s
test nightly	47s
test nightly --all-features	59s
test 1.81 --no-default-features	56s
test 1.81	59s
	11m 29s

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