Fix deprecation warning with pint 0.24

[ManuelHu]

The 0.24 release of pint (some days ago) deprecates the default_format attribute of the registry

• The replacement UnitRegistry.formatter also has been added only to 0.24: https://github.com/hgrecco/pint/commit/6c3716f3911015ddf7e3880ac688b1ed76d438e3
• The deprecation warning is from https://github.com/hgrecco/pint/commit/17c2143386349fc503d6b01b4b84d8db85ed06df

So add a conditional check to set the correct (non-deprecated) attribute depending on pint version

[ManuelHu]

successfully tested with my container with pint 0.23