Fix broken docs-build by pinning apache-airflow==2.10.2 (#1033)

Summary:
Pull Request resolved: #1033

`apache-airflow>2.6.3` (installed in `docs/requirements.txt`) transitively brings in `opentelemetry` which depends on `protobuf>=4.x`. This version of `protobuf` conflicts with the one required by `kfp==1.8.x` (`protobuf <= 3.20.x`).

What we oughta do is to upgrade to `kfp-2.x` but that's a much more intrusive change as we are bumping major versions. So pin to `apache-airflow==2.6.3` so that protobuf doesn't conflict with kfp.

Reviewed By: tonykao8080

Differential Revision: D72016216

Author: kiukchung

.github/workflows/doc-build.yaml

@@ -20,16 +20,15 @@ jobs:
           architecture: x64
       - name: Checkout TorchX
         uses: actions/checkout@v2
+      - name: Install TorchX
+        run: |
+          pip install -e .[dev]
       - name: Install Dependencies
         run: |
           set -eux
           sudo apt-get update
           sudo apt-get install -y pandoc
-          pip install -e .[dev]
           pip install -r docs/requirements.txt
-      - name: Install TorchX
-        run: |
-          python setup.py develop
       - name: Start Airflow
         run: |
           # start airflow in background

docs/requirements.txt

@@ -10,4 +10,7 @@ jupytext
 ipython_genutils
 # https://github.com/jupyter/nbconvert/issues/1736
 jinja2>=3.1.4
-apache-airflow
+# higher versions of airflow brings in opentelemetry which depends
+# a version of protobuf incompatible with pinned kfp in dev-requirements.txt
+apache-airflow==2.10.2
+protobuf==3.20.3