chore(deps): update dependency rollup to v2.51.0

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
rollup (source)	2.50.6 -> 2.51.0

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Release Notes

rollup/rollup

### [`v2.51.0`](https://togithub.com/rollup/rollup/blob/master/CHANGELOG.md#​2510) [Compare Source](https://togithub.com/rollup/rollup/compare/v2.50.6...v2.51.0) *2021-06-06* ##### Features - Add a helper for IntelliSense support in config files ([#​4127](https://togithub.com/rollup/rollup/issues/4127)) ##### Bug Fixes - Improve performance when generating source maps ([#​4122](https://togithub.com/rollup/rollup/issues/4122)) ##### Pull Requests - [#​4122](https://togithub.com/rollup/rollup/pull/4122): User Map to optimize performance ([@​izevo](https://togithub.com/izevo)) - [#​4127](https://togithub.com/rollup/rollup/pull/4127): Export defineConfig defines the auxiliary function of the configuration ([@​rxliuli](https://togithub.com/rxliuli))

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