refactor: do not use future-deprecated `DATE_RFC7231` constant (#9657) #13472

Job	Run time
Setup PHP Version for Code Coverage	4s
Others (8.1) / Sanity Tests	2m 36s
Others (8.2) / Sanity Tests	4m 7s
Others (8.4) / Sanity Tests	2m 20s
Others (8.3) / Sanity Tests	4m 37s
SeparateProcess (8.1) / tests	3m 45s
SeparateProcess (8.2) / tests	3m 44s
SeparateProcess (8.4) / tests	4m 48s
SeparateProcess (8.3) / tests	3m 30s
DatabaseLive (8.1, Postgre, 8.0) / tests	2m 48s
DatabaseLive (8.1, SQLite3, 8.0) / tests	2m 51s
DatabaseLive (8.4, SQLSRV, 8.0) / tests	5m 0s
DatabaseLive (8.4, OCI8, 8.0) / tests	6m 22s
DatabaseLive (8.3, Postgre, 8.0) / tests	2m 45s
DatabaseLive (8.3, OCI8, 8.0) / tests	6m 32s
DatabaseLive (8.1, OCI8, 8.0) / tests	6m 40s
DatabaseLive (8.1, MySQLi, 8.0) / tests	4m 15s
DatabaseLive (8.4, MySQLi, 8.0) / tests	5m 45s
DatabaseLive (8.2, MySQLi, 8.0) / tests	5m 5s
DatabaseLive (8.1, SQLSRV, 8.0) / tests	5m 51s
DatabaseLive (8.2, SQLSRV, 8.0) / tests	5m 31s
DatabaseLive (8.3, MySQLi, 8.0) / tests	4m 50s
DatabaseLive (8.2, Postgre, 8.0) / tests	3m 23s
DatabaseLive (8.3, SQLSRV, 8.0) / tests	4m 42s
DatabaseLive (8.2, SQLite3, 8.0) / tests	3m 10s
DatabaseLive (8.4, Postgre, 8.0) / tests	2m 55s
DatabaseLive (8.2, OCI8, 8.0) / tests	6m 57s
DatabaseLive (8.3, SQLite3, 8.0) / tests	3m 21s
CacheLive (8.1) / Cache Live Tests	2m 7s
CacheLive (8.2) / Cache Live Tests	2m 21s
DatabaseLive (8.1, MySQLi, 5.7) / tests	3m 19s
DatabaseLive (8.4, SQLite3, 8.0) / tests	2m 45s
CacheLive (8.3) / Cache Live Tests	2m 18s
CacheLive (8.4) / Cache Live Tests	2m 4s
Upload coverage results to Coveralls / coveralls	41s
	2h 13m 49s

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