Downgrade pub/sub emulator version in CI. (#2096)
Downgrade pub/sub emulator version in CI. (#2096)

For https://github.com/google/clusterfuzz/issues/2077.

google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz,google/clusterfuzz