Linux installation issues: nbconvert version

[sdxiang2]

Hi all, I'm running into the following installation error on Linux:

Could not find a version that satisfies the requirement nbconvert>=6.0 (from jupyter-contrib-nbextensions==0.7.0) (from versions: 4.0.0, 4.1.0, 4.2.0, 4.3.0, 5.0.0b1, 5.0.0, 5.1.0, 5.1.1, 5.2.1, 5.3.0, 5.3.1, 5.4.0, 5.4.1.dev0, 5.4.1, 5.5.0, 5.6.0, 5.6.1)
No matching distribution found for nbconvert>=6.0 (from jupyter-contrib-nbextensions==0.7.0)

My current nbconvert version is 7.2.9. Will this version be supported in the near future, or should I downgrade it to 5.6.1? Will downgrading cause issues with the functionality of my existing notebooks?

Thanks in advance!