Update install_manager.php

[adarshvs]

Corrected permissions check response to request user enable write permission for spear/config folder instead of the entire spear folder. This ensures easier troubleshooting as the install button remains disabled until all requirements are met.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

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