Force install of the git sha of flytekit for plugins (#721)

Signed-off-by: Yee Hing Tong <[email protected]>

.github/workflows/pythonbuild.yml

@@ -89,8 +89,8 @@ jobs:
         python -m pip install --upgrade pip==21.2.4 setuptools wheel
         make setup
         cd plugins/${{ matrix.plugin-names }}
-        # install in develop mode so setuptools doesn't override flytekit on current branch
         pip install -e .
+        pip install --no-deps -U https://github.com/flyteorg/flytekit/archive/${{ github.sha }}.zip#egg=flytekit
         pip freeze
     - name: Test with coverage
       run: |