chore(deps): update dependency google-api-python-client to v2.18.0 (#1495)

diff --git a/samples/compute/requirements.txt b/samples/compute/requirements.txt
index 24e75e8..a1c3b19 100644
--- a/samples/compute/requirements.txt
+++ b/samples/compute/requirements.txt
@@ -1,3 +1,3 @@
-google-api-python-client==2.17.0
+google-api-python-client==2.18.0
 google-auth==2.0.1
 google-auth-httplib2==0.1.0