PSR-4 autoloading error when installing Laravel bagisto-delivery-time-slot package manually

I’m trying to install a custom Laravel package locally by placing it inside the packages/ directory of my Laravel project.

Here’s what I’ve done so far:

I added the package to packages/Webkul/DeliveryTimeSlot

Updated my main composer.json file with the PSR-4 autoload configuration:

"autoload": {
"psr-4": {
    "App\": "app/",
    "Webkul\DeliveryTimeSlot\": "packages/Webkul/DeliveryTimeSlot/src/"
} }

After running:

composer dump-autoload

I receive the following warning:

Class CreateDeliveryTimeSlotsTable located in ./packages/Webkul/DeliveryTimeSlot/src/Database/Migrations/2020_01_27_001254_create_delivery_time_slots_table.php does not comply with psr-4 autoloading standard (rule: WebkulDeliveryTimeSlot => ./packages/Webkul/DeliveryTimeSlot/src). Skipping.

Class CreateDeliveryTimeSlotsOrdersTable located in ./packages/Webkul/DeliveryTimeSlot/src/Database/Migrations/2020_01_30_001255_create_delivery_time_slots_orders_table.php does not comply with psr-4 autoloading standard (rule: WebkulDeliveryTimeSlot => ./packages/Webkul/DeliveryTimeSlot/src). Skipping.

Here’s the relevant directory structure:

packages/
└── Webkul/
    └── DeliveryTimeSlot/
        └── src/
            └── Database/
                └── Migrations/
                    ├── 2020_01_27_001254_create_delivery_time_slots_table.php
                    └── 2020_01_30_001255_create_delivery_time_slots_orders_table.php

It looks like the issue is with PSR-4 autoloading for the migration classes. Do I need to define namespaces in those migration files? If so, what should the correct namespace be?

Thanks in advance for your help!