Add PHP 8.5 to CI matrix

[phpstan-bot]

Summary

• Add PHP 8.5 to the CI matrix in all three applicable jobs: lint, tests, and static-analysis
• This ensures the extension is tested with all PHP versions between 7.4 and 8.5

Test plan

• Verify the lint job runs on PHP 8.5
• Verify the tests job runs on PHP 8.5 (both lowest and highest dependencies)
• Verify the static-analysis job runs on PHP 8.5 (both lowest and highest dependencies)

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