3.0.0 Beta 11

• Removed circular dependency on amphp/phpunit-util (#408).
• Added stack-trace of Future creation to UnhandledFutureError which is defined only when assertions are enabled (#405).
• Strict types now declared in all library files. This will affect callbacks invoked within this library's code which use scalar types as parameters. Functions used with Amp\async() are the most likely to be affected by this change — these functions will now be invoked within a strict-types context.