chore: add a witness for `enum_variant_missing` #2936

Job	Run time
Build binary	29s
Semver: core-graphics	46s
Build binary (Windows)	2m 12s
Check lint and rustfmt	29s
Check if version changed	19s
Run tests (1.77, false)	3m 27s
Run tests (1.78, false)	3m 34s
Run tests (1.79, false)	3m 18s
Run tests (1.80, false)	3m 36s
Run tests (1.81, false)	3m 40s
Run tests (stable, false)	3m 30s
Run tests (beta, false)	3m 31s
Run tests (nightly, true)	3m 34s
Caching across rustdoc versions	1m 28s
Check failure when installed rustc is too old	15s
Semver: bevy_core v0.9.0	41s
Caching with feature config changed	30s
Semver: bevy_gltf v0.9.1	58s
Semver: clap v3.2.0	54s
Semver: libp2p-dcutr 1.62.0 and libp2p-relay 0.14.0	1m 6s
Semver: libp2p-gossipsub ~0.44.0 + libp2p-request-response ~0.24.0	1m 13s
Semver: libp2p-uds 0.37.0	52s
Semver: dependency has warnings with "-Dwarnings" (libp2p v0.53.1)	1m 9s
Semver: perf-event-open-sys2 v5.0.0	24s
Semver: ref-slice fork (git)	26s
Semver: libp2p-core 0.37.0	4m 51s
Semver: ref-slice fork (sparse)	19s
Semver: sqllogictest v0.13.0	33s
Semver: tokio ~v1.25.0 (explicit)	6s
Semver: tokio ~v1.25.0 (implicit)	2s
Semver: ref-slice fork (Windows) (git)	55s
Semver: ref-slice fork (Windows) (sparse)	57s
All CI stages	1s
Check for semver compliance	1s
Run the release workflow	1s
	50m 7s

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