chore(deps): bump libexpat to 2.6.4 #38480

Job	Run time
Metadata	11s
build / Build dependencies	8s
PDK tests	3m 57s
Lint and Doc tests	16s
Schedule busted tests to run	9s
Busted test runner 1	16m 7s
Busted test runner 2	16m 59s
Busted test runner 3	17m 10s
Busted test runner 4	16m 8s
Busted test runner 5	16m 12s
Busted test runner 6	16m 4s
Busted test runner 7	16m 1s
Cleanup and Luacov stats aggregator	0s
	1h 59m 22s

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