[10.x] Fix Cache DatabaseStore::add() error occur on Postgres within transaction

[xdevor]

Problem

similar to the previous PR, when using Postgres as the Cache database store,
an error occurs when performing Cache::add() operation on an already existing cache key within transaction.

PS. i make a integration test to prove this bug here

Steps To Reproduce

• Step 1: after setup postgres and .env file put the following code to laravel routes/console.php

use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\DB;

Artisan::command('test', function () {
    $store = Cache::store('database');

    $store->add('test-key', 'test-value', 60);
    
    DB::beginTransaction();
    $store->add('test-key', 'new-test-value', 60);
    DB::commit();

});

• Step 2: run php artisan test and the error will show

Solution

• call get() before insert() not only check cache exist but also get() will delete expired record in DB, therefor no need to update expired record in error handle statement which the root cause of PG error

Versions

• Postgres: v12 and v16
• PHP: 8.2
• Laravel: 10