add `Unknown` transaction variant #3708

Job	Run time
publish-check	12s
Check Changelog	8s
cargo-toml-fmt-check	12s
cargo_audit	9s
rustfmt	53s
cargo	0s
Publish code coverage report on GitHub pages branch	0s
publish-wasm-packages-check	4m 41s
verifications-complete	0s
publish	0s
publish_wasm_packages	0s
	6m 15s

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