Fix to_dataframe for TermSetWrapper #1623

Job	Run time
linux-gallery-python3.12-upgraded	55s
linux-gallery-python3.8-minimum	46s
windows-gallery-python3.12-upgraded	2m 12s
windows-gallery-python3.8-minimum	1m 43s
linux-python3.12	1m 34s
linux-python3.12-upgraded	1m 38s
linux-python3.8-minimum	1m 13s
macos-python3.12-upgraded	2m 53s
macos-python3.8-minimum	2m 47s
windows-python3.12-upgraded	2m 16s
windows-python3.8-minimum	1m 56s
linux-gallery-python3.12-ros3	1m 33s
conda-linux-python3.12-upgraded	2m 11s
conda-linux-python3.8-minimum	2m 2s
Deploy pre-release from dev	0s
	25m 39s

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