emoji_eventsBuild order (topological sort)

A build system knows which tasks depend on which: deps["deploy"] = ["test", "build"] means test and build must run before deploy. Write build_order(deps) that returns a list with every task exactly once, each after all of its dependencies.

• Tasks that only appear as dependencies are tasks too.
• When several tasks are ready at the same time, take them in alphabetical order, so the result is deterministic.
• If there is a cycle, raise ValueError whose message names the tasks in the cycle (any order is fine, e.g. "cycle: a, b, c").

Acceptance criteria

• The tests at the bottom print All tests passed.

Hint: Kahn's algorithm with a heapq of ready tasks.