Update test pip wheel package ci job: upgrade pip before testing.

.gitlab-ci.yml

@@ -667,6 +667,7 @@ test_linux_pkg_release:
     - source test_pyfaust-$CI_COMMIT_TAG/bin/activate
     - PYVER=$($JOB_PYTHON --version | awk '{print $2}' | sed -e 's/\.//g;s/\(..\).*/\1/')
     - SYS=$(if uname -a | grep -q Darwin; then echo macosx; else echo linux; fi)
+    - $JOB_PYTHON -m pip install --upgrade pip
     - $JOB_PYTHON -m pip install --upgrade build/wrapper/python/dist/${PYFAUST_PKG_NAME}-$CI_COMMIT_TAG-*$PYVER*$SYS*.whl
     - $JOB_PYTHON -c "import pyfaust; print(pyfaust.version()); print(pyfaust.rand(5,5).toarray());"
     - $JOB_PYTHON -c "import pyfaust.tests; pyfaust.tests.run_tests('cpu', 'double')"