chore(tests): upgrade environment test script from python3.6 (#1054)

.kokoro/environment_tests.sh

@@ -26,6 +26,7 @@ fi
 
 # make sure submodule is up to date
 cd "$PROJECT_ROOT"
+git config --global --add safe.directory '*'
 git submodule update --init --recursive
 cd "${PROJECT_ROOT}/env-tests-logging"
 
@@ -48,11 +49,11 @@ gcloud config set compute/zone us-central1-b
 gcloud auth configure-docker -q
 
 # Remove old nox
-python3.6 -m pip uninstall --yes --quiet nox-automation
+python3 -m pip uninstall --yes --quiet nox-automation
 
 # Install nox
-python3.6 -m pip install --upgrade --quiet nox
-python3.6 -m nox --version
+python3 -m pip install --upgrade --quiet nox
+python3 -m nox --version
 
 # Install kubectl
 if [[ "${ENVIRONMENT}" == "kubernetes" ]]; then
@@ -70,7 +71,7 @@ echo $ENVCTL_ID
 
 # Run the specified environment test
 set +e
-python3.6 -m nox --session "tests(language='java', platform='$ENVIRONMENT')"
+python3 -m nox --session "tests(language='java', platform='$ENVIRONMENT')"
 TEST_STATUS_CODE=$?
 
 # destroy resources