Update `yiisoft/widget` to `2.0`

[rustamwin]

Q	A
Is bugfix?	❌
New feature?	✔️
Breaks BC?	✔️
Fixed issues	comma-separated list of tickets # fixed by the PR, if any

[samdark]

Tests are to be fixed.

[codecov[bot]]

Codecov Report

Base: 97.26% // Head: 97.26% // Decreases project coverage by -0.01% :warning:

Coverage data is based on head (cb57853) compared to base (2301b15). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #101 +/- ## ============================================ - Coverage 97.26% 97.26% -0.01% + Complexity 446 444 -2 ============================================ Files 18 18 Lines 1574 1570 -4 ============================================ - Hits 1531 1527 -4 Misses 43 43 ``` | [Impacted Files](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft) | Coverage Δ | | |---|---|---| | [src/Widget.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL1dpZGdldC5waHA=) | `100.00% <ø> (ø)` | | | [src/Accordion.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0FjY29yZGlvbi5waHA=) | `93.75% <100.00%> (-0.09%)` | :arrow_down: | | [src/Alert.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0FsZXJ0LnBocA==) | `95.45% <100.00%> (ø)` | | | [src/Breadcrumbs.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0JyZWFkY3J1bWJzLnBocA==) | `100.00% <100.00%> (ø)` | | | [src/Button.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0J1dHRvbi5waHA=) | `100.00% <100.00%> (ø)` | | | [src/ButtonDropdown.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0J1dHRvbkRyb3Bkb3duLnBocA==) | `100.00% <100.00%> (ø)` | | | [src/ButtonGroup.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0J1dHRvbkdyb3VwLnBocA==) | `100.00% <100.00%> (ø)` | | | [src/ButtonToolbar.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0J1dHRvblRvb2xiYXIucGhw) | `100.00% <100.00%> (ø)` | | | [src/Carousel.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0Nhcm91c2VsLnBocA==) | `100.00% <100.00%> (ø)` | | | [src/Dropdown.php](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft#diff-c3JjL0Ryb3Bkb3duLnBocA==) | `100.00% <100.00%> (ø)` | | | ... and [7 more](https://codecov.io/gh/yiisoft/yii-bootstrap5/pull/101?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft) | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=yiisoft)

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[samdark]

👍