updating to python 3.8 after rebasing on latest master

ci/docker/Dockerfile.build.ubuntu

@@ -74,7 +74,8 @@ RUN export DEBIAN_FRONTEND=noninteractive && \
         libnuma-dev \
         ## Frontend languages
         # Python
-        python3 \
+        python3.8 \
+        python3.8-dev
         python3-pip \
         ## Documentation
         doxygen \
@@ -98,6 +99,8 @@ RUN cd /usr/local/src && \
     cd /usr/local/src && \
     rm -rf ccache
 
+RUN rm /usr/bin/python3 && ln -s /usr/bin/python3.8 /usr/bin/python3
+
 # RAT License Checker tool
 RUN cd /usr/local/src && \
     wget https://archive.apache.org/dist/creadur/apache-rat-0.13/apache-rat-0.13-bin.tar.gz && \

ci/docker/install/requirements

@@ -25,17 +25,19 @@ graphviz<0.9.0,>=0.8.1
 contextvars;python_version<"3.7"
 
 # Optional dependencies
-onnx==1.5.0
+onnx==1.5.0;python_version<"3.8"
+onnx==1.7.0;python_version<"3.8"
 # protobuf version frozen due to ps-lite
 protobuf==3.5.2
 scipy==1.4.1
 tabulate==0.7.5
-Cython==0.29.7
+Cython==0.29.7;python_version<"3.8"
+Cython==0.29.19;python_version=="3.8"
 
 # Development dependencies
 cpplint==1.3.0
-pylint==2.3.1  # pylint and astroid need to be aligned
-astroid==2.3.3  # pylint and astroid need to be aligned
+pylint==2.5.1  # pylint and astroid need to be aligned
+astroid==2.4.2  # pylint and astroid need to be aligned
 pytest==5.3.5
 pytest-env==0.6.2
 pytest-cov==2.8.1
@@ -54,4 +56,5 @@ boto3==1.9.229
 h5py==2.10.0
 # TODO(szha): remove once clean-up for py2 is complete
 six==1.11.0
-Pillow<6
+Pillow<6;python_version<"3.8"
+Pillow==7.1.2;python_version=="3.8"