build: release on node 18 (#2129)

* build: release on node 18

* ignore publish config template

Author: chingor13

.kokoro/release/publish.cfg

@@ -24,6 +24,7 @@
   '.prettierignore',
   '.prettierrc',
   '.nycrc',
+  '.kokoro/release/publish.cfg',
   '.kokoro/presubmit/node10/system-test.cfg',
   '.kokoro/continuous/node10/system-test.cfg',
   '.kokoro/system-test.sh',