Add funding acknowledgement in pint-xarray post (#628)

* acknowledge Moore foundation funding

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: TomNicholas

src/posts/introducing-pint-xarray/index.md

@@ -293,3 +293,7 @@ If you have usage questions you can raise them there, on the [Xarray discussions
 
 The work here to allow Xarray to wrap Pint objects is part of a [broader effort to generalise Xarray](http://xarray.pydata.org/en/stable/roadmap.html#flexible-arrays) to handle a wide variety of data types (so-called "duck array wrapping").
 Along with the incoming [support for flexible indexes](http://xarray.pydata.org/en/stable/roadmap.html#flexible-indexes), we are excited for all the new features that this will enable for Xarray users!
+
+## Acknowledgements
+
+Tom Nicholas' work on this project was by the Gordon and Betty Moore Foundation Data-Driven Discovery program, via a grant to the [Columbia Climate Data Science Lab](https://ocean-transport.github.io/cds_lab.html).