🐛 Source should be unique for each feedProvider

The tagged locator uses the source as an index to retrieve the
corresponding feedprovider. If there is a source that points to multiple
services the locator fetches the first one it encounters. This results
in the second feed not being fetched.

AFAIK Symfony does not provide a locator that can fetch multiple
services by index.

There are multiple solutions to this problem:

- We could have the php.watch feed provider fetch both feeds.
- We could keep both the providers and give them a unique source.

In this commit we decided on the latter. We introduce two new sources,
php.watch-changes and php.watch-news.

migrations/Version20231231123959.php

@@ -0,0 +1,37 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20231231123959 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return '';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // Delete 'php.watch' source
+        $this->addSql("DELETE FROM sources WHERE id='9930338f-d07c-4030-ade6-5ac19821e554'");
+
+        $this->addSql("INSERT INTO sources (id, name) VALUES ('a9ba164c-5a86-43d2-b024-f38e6a227a41', 'php.watch-news')");
+        $this->addSql("INSERT INTO sources (id, name) VALUES ('18929b96-79a4-44bf-8d97-f442851b7b44', 'php.watch-changes')");
+
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->addSql("INSERT INTO sources (id, name) VALUES ('9930338f-d07c-4030-ade6-5ac19821e554','php.watch')");
+
+        $this->addSql("DELETE FROM sources WHERE id='a9ba164c-5a86-43d2-b024-f38e6a227a41'");
+        $this->addSql("DELETE FROM sources WHERE id='18929b96-79a4-44bf-8d97-f442851b7b44'");
+    }
+}

src/Feed/Application/Service/FeedProvider/PhpWatchChangesFeedProvider.php

@@ -20,7 +20,7 @@ public function __construct(
 
     public static function getSource(): string
     {
-        return 'php.watch';
+        return 'php.watch-changes';
     }
 
     public function fetchFeedItems(): array

src/Feed/Application/Service/FeedProvider/PhpWatchNewsFeedProvider.php

@@ -20,7 +20,7 @@ public function __construct(
 
     public static function getSource(): string
     {
-        return 'php.watch';
+        return 'php.watch-news';
     }
 
     public function fetchFeedItems(): array