Dtale

* [428](https://github.com/man-group/dtale/pull/428): Turn global_state into interfaces
* [434](https://github.com/man-group/dtale/issues/434): Additional PPS formatting
* [433](https://github.com/man-group/dtale/issues/433): fixed exception message display in merge UI
* [432](https://github.com/man-group/dtale/issues/432): updated calls to "get_instance" in merge code snippets
* [431](https://github.com/man-group/dtale/issues/431): fixed stacking code example
* [430](https://github.com/man-group/dtale/issues/430): replace empty strings with nans when converting dates to timestamp floats

* [261](https://github.com/man-group/dtale/issues/261): Merging & Stacking UI

* [423](https://github.com/man-group/dtale/issues/423): y-axis scale toggle
* [422](https://github.com/man-group/dtale/issues/422): sheet selection on excel uploads
* [421](https://github.com/man-group/dtale/issues/421): replacements not replacing zeroes

* [420](https://github.com/man-group/dtale/issues/420): Added python2.7 support back
* [416](https://github.com/man-group/dtale/issues/416): aggregating charts by "first" or "last"
* [415](https://github.com/man-group/dtale/issues/415): fix display of heatmap option on main menu when column heatap on

* Excel Uploads
* Removed python2.7 support from code
* CI Updates:
* updated JS workflow to use latest node image
* dropped support for python 2.7 and added support for python 3.9
* Jest test refactoring
* [415](https://github.com/man-group/dtale/issues/415): single column heatmap
* [414](https://github.com/man-group/dtale/issues/414): exporting charts using "top_bars"
* [413](https://github.com/man-group/dtale/issues/413): Q-Q Plot
* [411](https://github.com/man-group/dtale/issues/411): updates for column analysis warnings
* [412](https://github.com/man-group/dtale/issues/412): histogram for date columns
* [404](https://github.com/man-group/dtale/issues/404): fixes for group input display on floats and data frequencies

* [408](https://github.com/man-group/dtale/issues/408): modifications to exponential smoothing column builder UI
* [405](https://github.com/man-group/dtale/issues/405): removed cleaners from non-string columns)
* [404](https://github.com/man-group/dtale/issues/404): fixed bug with missing group selection dropdown on strings)
* [406](https://github.com/man-group/dtale/issues/406): handling for duplicate bins