Total issues resolved: 7

• 2505: Add PHPStan (config) and some fixes thanks to @tersmitten
• 2519: Added getBasePath method to Router thanks to @chantron
• 2520: Put HeaderStackTestAsset into Slim\Tests\Asset namespace thanks to @akrabat
• 2528: Update route group $callable parameter type thanks to @ugokoli
• 2532: Test with PHP 7.3 thanks to @tuupola
• 2543: Ensure PSR-7 stream read() is called with an int argument per spec thanks to @soren121
• 2558: Bug fix: Ensure integer is passed to read() thanks to @farpat