Fix Python and Conan versions for sigstore signing on CentOS 7 #571

Job	Run time
Windows no CUDA <config=Release>	1m 45s
Linux CentOS 7 VFX CY2021 <config=Release>	2m 19s
Linux Rocky 8 VFX CY2023 No OpenGL <config=Release>	4m 6s
Linux Ubuntu <config=Release>	38s
Linux CentOS 7 VFX CY2022 <config=Release>	2m 8s
Linux Rocky 8 VFX CY2023 <config=Release>	3m 24s
Windows <config=Release>	3m 50s
MacOS <config=Release>	2m 37s
Linux CentOS 7 VFX CY2022 <config=Release>	3m 5s
Linux Ubuntu <config=Release>	1m 42s
Linux CentOS 7 VFX CY2021 <config=Release>	2m 23s
Linux Rocky 8 VFX CY2023 No OpenGL <config=Release>	4m 6s
Windows <config=Release>	3m 50s
MacOS <config=Release>	2m 37s
Windows no CUDA <config=Release>	1m 45s
Linux Rocky 8 VFX CY2023 <config=Release>	3m 24s
Linux Rocky 8 VFX CY2023 <config=Release>	3m 24s
Linux CentOS 7 VFX CY2021 <config=Release>	2m 43s
Linux Rocky 8 VFX CY2023 No OpenGL <config=Release>	4m 6s
Linux Ubuntu <config=Release>	1m 42s
MacOS <config=Release>	2m 37s
Windows <config=Release>	3m 50s
Windows no CUDA <config=Release>	1m 45s
Linux CentOS 7 VFX CY2022 <config=Release>	3m 5s
	1h 6m 51s

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