Joining the party late, but just as a complement, I ran into some problems with Seaborn not so long ago, because CoLab installed a version with !pip that wasn't updated. In my specific case, I couldn't use Scatterplot, for example. The answer to this is below:
To install the module, all you need is:
!pip install seaborn
To upgrade it to the most updated version:
!pip install --upgrade seaborn
If you want to install a specific version
!pip install seaborn==0.9.0
I believe all the rules common to pip apply normally, so that pretty much should work.