Added Dijkstra era #18233

Job	Run time
cabal-format	5s
Check branch history	13s
build (9.6.7, ubuntu-latest)	15m 37s
fourmolu	45s
gen-hie	7m 29s
build (9.8.4, ubuntu-latest)	13m 49s
build (9.10.2, ubuntu-latest)	3m 10s
build (9.12.2, ubuntu-latest)	3m 34s
Check if formal-ledger-specifications SRP is valid	9s
${{ matrix.package }}-${{ matrix.ghc }}-${{ matrix.os }}	0s
codegen	0s
Tests completed	1s
Send a slack notification on \#ledger-internal if the nightly build failed	0s
	44m 52s

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