putting myst-nb latest install in ci

Author: AakashGfude

.github/workflows/ci.yml

@@ -15,6 +15,12 @@ jobs:
           python-version: 3.8
           environment-file: environment.yml
           activate-environment: lecture-datascience
+      - name: Install myst-nb
+        run: |
+          pip install git+https://github.com/executablebooks/MyST-NB@master
+      - name: Install sphinx
+        run: |
+          pip install sphinx==3.5.0
       - name: Display Conda Environment Versions
         shell: bash -l {0}
         run: conda list