Phan: try using 6.3 stubs #54365

Job	Run time
detect changed files	7s
Copied files are in sync	7s
Changelogger use	17s
Changelogger validity	53s
Project structure	1m 36s
PHP lint (7.0)	33s
PHP lint (7.2)	29s
PHP lint (7.4)	29s
PHP Code Sniffer (non-excluded files only)	1m 48s
PHP lint (8.0)	30s
PHP lint (8.1)	39s
PHP lint (8.2)	32s
PHP Compatibility	1m 9s
PHP lint (8.3)	28s
ESLint (non-excluded files only)	0s
PHP Code Sniffer (changes to excluded files only)	0s
Check linter exclude lists	1m 48s
ESLint (changes to excluded files only)	0s
Lint GitHub Actions yaml files	0s
Lock files are up to date	2m 0s
Monorepo package version refs	1m 15s
	14m 40s

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