chore: update PHPUnit version in CHANGELOG and fix README example

Updated PHPUnit from ^11.4.0 to ^11.5.50 in the CHANGELOG. Corrected the README example for bulkCandles to use separate array elements for symbols instead of a single string.

Author: MarketDataApp

CHANGELOG.md

@@ -280,7 +280,7 @@ New required dependencies:
 - `vlucas/phpdotenv: ^5.5` - Environment file support
 
 Updated development dependencies:
-- `phpunit/phpunit: ^11.4.0` (was ^10.3.2)
+- `phpunit/phpunit: ^11.5.50` (was ^10.3.2)
 
 ### Bug Fixes
 

README.md

@@ -91,7 +91,7 @@ $client = new MarketDataApp\Client('your_api_token');
 
 // Stocks
 $candles = $client->stocks->candles('AAPL');
-$bulk_candles = $client->stocks->bulkCandles(['AAPL, MSFT']);
+$bulk_candles = $client->stocks->bulkCandles(['AAPL', 'MSFT']);
 $quote = $client->stocks->quote('AAPL');
 $quotes = $client->stocks->quotes(['AAPL', 'MSFT']);
 $earnings = $client->stocks->earnings(symbol: 'AAPL', from: '2023-01-01');