Updating Requirements (#1)

* Pin isis version to 3.9

* Used custom mknotebooks build

---------

Co-authored-by: Austin Sanders <arsanders@usgs.gov>

docs/how-to-guides/environment-setup-and-maintenance/installing-isis-via-anaconda.md

@@ -27,7 +27,7 @@ This installation guide is for ISIS users interested in installing ISIS (3.6.0)+
     export CONDA_SUBDIR=osx-64
     
     #Create a new conda environment to install ISIS in
-    conda create -n isis
+    conda create -n isis python=3.9
 
     #Activate the environment
     conda activate isis

requirements.txt

@@ -3,4 +3,4 @@ mkdocs-material
 neoteroi-mkdocs
 codespell
 linkchecker
-mknotebooks
+git+https://github.com/Kelvinrr/mknotebooks.git