Fix local pipeline (#2604)

src/sdk/pynni/nni/ppo_tuner/requirements.txt

 enum34
 gym
-tensorflow
\ No newline at end of file

test/pipelines/pipelines-it-local-tf2.yml

@@ -12,7 +12,7 @@ jobs:
       set -e
       python3 -m pip install scikit-learn==0.20.0 --user
       python3 -m pip install torch==1.3.1 torchvision==0.4.1 -f https://download.pytorch.org/whl/torch_stable.html --user
-      python3 -m pip install tensorflow-gpu==2.2.0 --user
+      python3 -m pip install tensorflow-gpu==2.2.0 tensorflow-estimator==2.2.0 --force --user
       python3 -m pip install keras==2.4.2 --user
       sudo apt-get install swig -y
       PATH=$HOME/.local/bin:$PATH nnictl package install --name=SMAC

test/pipelines/pipelines-it-local-windows.yml

@@ -10,7 +10,7 @@ jobs:
       python -m pip install scikit-learn==0.20.0 --user
       python -m pip install keras==2.1.6 --user
       python -m pip install torchvision===0.4.1 torch===1.3.1 -f https://download.pytorch.org/whl/torch_stable.html --user
-      python -m pip install tensorflow-gpu==1.15.2 --user
+      python -m pip install tensorflow-gpu==1.15.2 tensorflow-estimator==1.15.1 --force --user
     displayName: 'Install dependencies for integration tests'
   - script: |
       cd test

test/pipelines/pipelines-it-local.yml

@@ -14,7 +14,7 @@ jobs:
       python3 -m pip install torchvision==0.4.1 --user
       python3 -m pip install torch==1.3.1 --user
       python3 -m pip install keras==2.1.6 --user
-      python3 -m pip install tensorflow-gpu==1.15.2 --user
+      python3 -m pip install tensorflow-gpu==1.15.2 tensorflow-estimator==1.15.1 --force --user
       sudo apt-get install swig -y
       PATH=$HOME/.local/bin:$PATH nnictl package install --name=SMAC
       PATH=$HOME/.local/bin:$PATH nnictl package install --name=BOHB