Added Dijkstra era #18223

Job	Run time
fourmolu	47s
cabal-format	5s
build (9.6.7, ubuntu-latest)	15m 20s
build (9.8.4, ubuntu-latest)	13m 38s
build (9.10.2, ubuntu-latest)	3m 12s
Check branch history	11s
build (9.12.2, ubuntu-latest)	3m 33s
gen-hie	7m 0s
Check if formal-ledger-specifications SRP is valid	7s
codegen	0s
${{ matrix.package }}-${{ matrix.ghc }}-${{ matrix.os }}	0s
Tests completed	1s
Send a slack notification on \#ledger-internal if the nightly build failed	0s
	43m 54s

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