Fix cddl for `update_committee` cold credential #16846

Job	Run time
fourmolu	46s
Check branch history	13s
cabal-format	9s
build (8.10.7, ubuntu-latest)	44m 48s
build (9.2.8, ubuntu-latest)	31m 19s
gen-hie	5m 41s
build (9.6.6, ubuntu-latest)	31m 34s
Check if formal-ledger-specifications SRP is valid	14s
build (9.8.4, ubuntu-latest)	22m 12s
build (9.10.1, ubuntu-latest)	22m 51s
${{ matrix.package }}-${{ matrix.ghc }}-${{ matrix.os }}	1s
Tests completed	1s
Send a slack notification on \#ledger-internal if the nightly build failed	1s
	2h 39m 50s

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