to_compact: support uncertainties' Magnitudes , keeping warning #1089

Job	Run time
test-macos (3.9)	1m 59s
test-linux (3.9)	1m 45s
test-macos (3.9, numpy>=1.21,<2.0.0)	3m 28s
test-macos (3.10)	1m 49s
test-linux (3.9, uncertainties==3.1.6)	1m 35s
test-windows (3.9, numpy>=1.21,<2.0.0)	49s
test-macos (3.10, numpy>=1.21,<2.0.0)	2m 36s
test-linux (3.9, uncertainties>=3.1.6,<4.0.0)	1m 45s
test-windows (3.10, numpy>=1.21,<2.0.0)	54s
test-macos (3.11)	1m 56s
test-linux (3.9, numpy>=1.21,<2.0.0)	2m 6s
test-windows (3.11, numpy>=1.21,<2.0.0)	53s
test-macos (3.11, numpy>=1.21,<2.0.0)	1m 58s
test-linux (3.9, numpy>=1.21,<2.0.0, uncertainties==3.1.6)	1m 57s
test-linux (3.9, numpy>=1.21,<2.0.0, uncertainties>=3.1.6,<4.0.0)	3m 20s
test-linux (3.10)	1m 57s
test-linux (3.10, uncertainties==3.1.6)	1m 58s
test-linux (3.10, uncertainties>=3.1.6,<4.0.0)	1m 44s
test-linux (3.10, numpy>=1.21,<2.0.0)	3m 7s
test-linux (3.10, numpy>=1.21,<2.0.0, uncertainties==3.1.6)	2m 16s
test-linux (3.10, numpy>=1.21,<2.0.0, uncertainties>=3.1.6,<4.0.0)	1m 59s
test-linux (3.11)	1m 30s
test-linux (3.11, uncertainties==3.1.6)	1m 56s
test-linux (3.11, uncertainties>=3.1.6,<4.0.0)	1m 52s
test-linux (3.11, numpy>=1.21,<2.0.0)	2m 33s
test-linux (3.11, numpy>=1.21,<2.0.0, uncertainties==3.1.6)	2m 12s
test-linux (3.11, numpy>=1.21,<2.0.0, uncertainties>=3.1.6,<4.0.0)	2m 38s
test-linux (3.9, numpy, matplotlib==2.2.5)	3m 4s
test-linux (3.9, numpy, uncertainties, sparse xarray netCDF4 dask[complete]==2023.4.0 graphviz ba...	2m 53s
	1h 0m 29s

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