Update dependency rollup to v2.50.1

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
rollup (source)	2.50.0 -> 2.50.1

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Release Notes

rollup/rollup

### [`v2.50.1`](https://togithub.com/rollup/rollup/blob/master/CHANGELOG.md#​2501) [Compare Source](https://togithub.com/rollup/rollup/compare/v2.50.0...v2.50.1) *2021-05-26* ##### Bug Fixes - Do not associate pure annotations in simplified expressions with wrong elements ([#​4095](https://togithub.com/rollup/rollup/issues/4095)) - Prevent invalid code when simplified conditionals start with an IIFE function expression ([#​4099](https://togithub.com/rollup/rollup/issues/4099)) ##### Pull Requests - [#​4095](https://togithub.com/rollup/rollup/pull/4095): Correctly associate pure annotations and remove invalid ones ([@​lukastaegert](https://togithub.com/lukastaegert)) - [#​4099](https://togithub.com/rollup/rollup/pull/4099): Wrap leading function expression iifes in conditionals ([@​lukastaegert](https://togithub.com/lukastaegert))

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