Read Only FS return false

Signed-off-by: Git'Fellow <12234510+solracsf@users.noreply.github.com>

lib/private/Setup.php

 			\OCP\Server::get(Installer::class)
 		);
 
+		if (!is_writable($setupHelper->pathToHtaccess())) {
+			return false;
+		}
+
 		$htaccessContent = file_get_contents($setupHelper->pathToHtaccess());
 		$content = "#### DO NOT CHANGE ANYTHING ABOVE THIS LINE ####\n";
 		$htaccessContent = explode($content, $htaccessContent, 2)[0];