Update dependency rollup to v2.23.1

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
rollup (source)	devDependencies	patch	2.23.0 -> 2.23.1

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Release Notes

rollup/rollup

### [`v2.23.1`](https://togithub.com/rollup/rollup/blob/master/CHANGELOG.md#​2231) [Compare Source](https://togithub.com/rollup/rollup/compare/v2.23.0...v2.23.1) _2020-08-07_ ##### Bug Fixes - Fix an issue where dynamically importing an entry point could return a malformed namespace for CJS and AMD formats ([#​3709](https://togithub.com/rollup/rollup/issues/3709)) ##### Pull Requests - [#​3709](https://togithub.com/rollup/rollup/pull/3709): Properly construct namespace when dynamically importing chunks with facades in default export mode ([@​lukastaegert](https://togithub.com/lukastaegert))

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