Remove mention to flyteidl@union_type in doc-requirements

Signed-off-by: Eduardo Apolinario <[email protected]>

.github/workflows/pythonbuild.yml

@@ -154,6 +154,5 @@ jobs:
         run: |
           python -m pip install --upgrade pip==21.2.4 setuptools wheel
           pip install -r doc-requirements.txt
-          git clone https://github.com/flyteorg/flyteidl.git && cd flyteidl && git checkout union_type && pip install . && cd ..
       - name: Build the documentation
         run: make -C docs html