Convert the `getSong` function to async function (instead of using `co.wrap`) in src/game/index.js

[github-actions[bot]]

See issue #575 for more details.

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This issue has been automatically created by todo-actions based on a TODO comment found in src/game/index.js:35. It will automatically be closed when the TODO comment is removed from the default branch (master).

[vanya829]

Hi. I want to get this one

[dtinth]

All done in #782