chore(deps): update dependency google-cloud-monitoring to v2.2.1 (#274)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [google-cloud-monitoring](https://togithub.com/googleapis/python-monitoring) | `==2.1.0` -> `==2.2.1` | [![age](https://badges.renovateapi.com/packages/pypi/google-cloud-monitoring/2.2.1/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/pypi/google-cloud-monitoring/2.2.1/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/pypi/google-cloud-monitoring/2.2.1/compatibility-slim/2.1.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/pypi/google-cloud-monitoring/2.2.1/confidence-slim/2.1.0)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>googleapis/python-monitoring</summary>

### [`v2.2.1`](https://togithub.com/googleapis/python-monitoring/blob/master/CHANGELOG.md#&#8203;221-httpswwwgithubcomgoogleapispython-monitoringcomparev220v221-2021-03-29)

[Compare Source](https://togithub.com/googleapis/python-monitoring/compare/v2.2.0...v2.2.1)

### [`v2.2.0`](https://togithub.com/googleapis/python-monitoring/blob/master/CHANGELOG.md#&#8203;220-httpswwwgithubcomgoogleapispython-monitoringcomparev210v220-2021-03-25)

[Compare Source](https://togithub.com/googleapis/python-monitoring/compare/v2.1.0...v2.2.0)

##### Features

-   add `client_cert_source_for_mtls` ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added `IstioCanonicalService` for service monitoring. ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added `total_size` to the response of `ListAlertPolicies`. ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added creation and mutation records to notification channels. ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added support for Monitoring Query Language ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added support for Monitoring Query Language ([#&#8203;101](https://www.github.com/googleapis/python-monitoring/issues/101)) ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added support for querying metrics for folders and organizations. ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added support for secondary aggregation when querying metrics. ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Added support for units in the `MetricService` ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))

##### Bug Fixes

-   Extended the default deadline for `UpdateGroup` to 180s. ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   Un-deprecated `cluster_istio` for service monitoring. ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))
-   use correct retry deadline ([0eb2ca6](https://www.github.com/googleapis/python-monitoring/commit/0eb2ca6b5044553c11d5f5e0f4859bf65387909b))

</details>

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samples/metricscaler/requirements.txt

@@ -1,2 +1,2 @@
 google-cloud-bigtable==1.7.0
-google-cloud-monitoring==2.1.0
+google-cloud-monitoring==2.2.1