Update dependency rollup to v2.56.1

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
rollup (source)	2.56.0 -> 2.56.1

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Release Notes

rollup/rollup

### [`v2.56.1`](https://togithub.com/rollup/rollup/blob/master/CHANGELOG.md#​2561) [Compare Source](https://togithub.com/rollup/rollup/compare/v2.56.0...v2.56.1) *2021-08-08* ##### Bug Fixes - Fix rendering of SystemJS export declarations initialized with a simplifiable expression ([#​4202](https://togithub.com/rollup/rollup/issues/4202)) ##### Pull Requests - [#​4202](https://togithub.com/rollup/rollup/pull/4202): Fix incorrect rendering of export declarations in SystemJS ([@​lukastaegert](https://togithub.com/lukastaegert))

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