[CodeQuality] Fix escape character on SimplifyRegexPatternRector #30716

Job	Run time
PHPStan	1m 21s
Run with Space in Directory	22s
Active Classes	21s
Preload php-parser Order	20s
Help and Version	29s
Composer Validate	17s
Commented Code	17s
Check no "*.php" files in rules Fixture directory	16s
Detect composer dependency issues	17s
Compatible PHPStan versions	21s
Check before/after test fixture on no-changes	22s
Finalize classes	24s
	5m 7s

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