Adds LICENSE file to tensorflow-serving-api python package.

It is recommended to include LICENSE file in the package.[1] But tensorflow-serving-api doesn't have one in it.

We need LICENSE file and recent versions of `wheel` will automatically pickup LICENSE file in local directory.

[1] https://packaging.python.org/tutorials/packaging-projects/#creating-a-license

PiperOrigin-RevId: 343562364
(cherry picked from commit 2b276fc)

Author: shadowdragon89

tensorflow_serving/tools/pip_package/build_pip_package.sh

@@ -72,10 +72,8 @@ function main() {
 
   echo "Adding package setup files"
   cp ${PIP_SRC_DIR}/setup.py "${TMPDIR}"
-  cp LICENSE "${TMPDIR}"
 
   pushd "${TMPDIR}"
-  python3 -m pip install --upgrade wheel -q
   echo $(date) : "=== Building wheel (CPU)"
   python3 setup.py bdist_wheel --universal \
     --project_name tensorflow-serving-api # >/dev/null