examples: deprecate actix3_example (#2154) #4138

Job	Run time
Clippy	1m 14s
Init	8s
Rustfmt	15s
Examples (examples/actix_example)	2m 39s
Unit Test	3m 16s
Examples (examples/axum_example)	2m 35s
Examples (examples/basic)	1m 17s
Examples (examples/graphql_example)	2m 46s
Examples (examples/jsonrpsee_example)	2m 34s
Examples (examples/loco_example)	3m 17s
Examples (examples/poem_example)	2m 19s
Examples (examples/proxy_gluesql_example)	1m 24s
Examples (examples/rocket_example)	3m 9s
Examples (examples/rocket_okapi_example)	3m 8s
Examples (examples/salvo_example)	2m 44s
Examples (examples/seaography_example)	2m 32s
Examples (examples/tonic_example)	2m 19s
Compile MySQL (actix, native-tls)	2m 45s
Compile SQLite (async-std, native-tls)	2m 51s
Compile MySQL (actix, rustls)	3m 1s
Compile SQLite (async-std, rustls)	3m 5s
Compile PostgreSQL (tokio, native-tls)	2m 52s
CLI	0s
Compile PostgreSQL (tokio, rustls)	3m 17s
Issues Matrix	0s
Issues	0s
MariaDB (10.6, actix, native-tls)	2m 15s
MySQL (8, actix, native-tls)	3m 10s
MySQL (5.7, actix, native-tls)	3m 26s
SQLite (async-std, native-tls)	4m 25s
SQLite (async-std, rustls)	4m 38s
Postgres (14.4, tokio, native-tls)	7m 18s
	1h 20m 39s

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