Bump Google Cloud and Prometheus client dependencies

[lawliet89]

Required for all PRs:

• Signed CLA.

• Associated README.md updated.

• Has appropriate unit tests.

• Include fix for Fix promhttp error handling prometheus/client_golang#726

For context, I am seeing endless lines from Telegraf due to Kubernetes liveness probes:

• Fixes Stackdriver input errors on "Failed iterating metric desciptor responses" and does not retry #7043
• Ran go mod tidy

[lawliet89]

Go 1.12 wants

        github.com/gogo/protobuf v1.2.2-0.20190723190241-65acae22fc9d
        github.com/golang/geo v0.0.0-20190916061304-5b978397cfec
        github.com/golang/protobuf v1.3.5
+       github.com/google/btree v1.0.0 // indirect
        github.com/google/go-cmp v0.4.0
        github.com/google/go-github v17.0.0+incompatible
        github.com/google/go-querystring v1.0.0 // indirect
+       github.com/gorilla/context v1.1.1 // indirect
        github.com/gorilla/mux v1.6.2
        github.com/gotestyourself/gotestyourself v2.2.0+incompatible // indirect
        github.com/hailocab/go-hostpool v0.0.0-20160125115350-e80d13ce29ed // indirect

in go.mod but 1.13 does not want that. Not sure how to reconcile the test failures.

[danielnelson]

I fixed the issues and updated these dependencies, would you be able to double check everything is working from the release candidate builds: https://github.com/influxdata/telegraf/releases/tag/v1.14.0-rc1

[lawliet89]

1.14 rc1 seems to be working fine