Release v6.0.1

• Bump symfony/twig-bridge from 5.4.22 to 5.4.31 in /modules/btcpay by @dependabot in #85
• Bump symfony/symfony from 4.4.50 to 4.4.51 by @dependabot in #86
• Ensure client is available in validation.php by @BitcoinMitchell in #87

Full Changelog: v6.0.0...v6.0.1

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Thank you @ndeet and nethek for testing.