Update stellar-xdr (#1467) #4240

Job	Run time
cargo-deny (advisories)	43s
cackle	1m 25s
check-git-rev-deps	8s
cargo-deny (bans licenses sources)	43s
build-and-test (msrv, 22, ubuntu-latest, wasm32-unknown-unknown, false)	9m 44s
build-and-test (msrv, 22, ubuntu-latest-16-cores, x86_64-unknown-linux-gnu, true)	21m 8s
fmt	10s
build-and-test (latest, 22, ubuntu-latest, wasm32-unknown-unknown, false)	11m 6s
semver-checks	4m 12s
build-and-test (latest, 22, ubuntu-latest-16-cores, x86_64-unknown-linux-gnu, true)	18m 40s
publish-dry-run (ubuntu-latest, wasm32-unknown-unknown) / publish-dry-run / publish-dry-run	17s
publish-dry-run (ubuntu-latest, x86_64-unknown-linux-gnu) / publish-dry-run / publish-dry-run	17s
complete	1s
	1h 8m 34s

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