chore: bump php to 8.5 and update ecosystem dependencies - #48

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, shivammathur/setup-php@15c43e89cdef867065b0213be354c2841860869e. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/