Prepare 1.4 release (#584)

* Prepare 1.4 release

* Apply suggestions from code review

Co-authored-by: NouemanKHAL <noueman.khalikine@datadoghq.com>

Co-authored-by: NouemanKHAL <noueman.khalikine@datadoghq.com>

CHANGELOG.md

@@ -1,5 +1,23 @@
 # Changelog
 
+## 1.4.O / 2021-09-14
+
+* [Added] Add restricted roles for Synthetics global variables. See [#550](https://github.com/DataDog/datadog-api-client-python/pull/550).
+* [Added] Add events data source to Dashboard widgets. See [#545](https://github.com/DataDog/datadog-api-client-python/pull/545).
+* [Added] Add support for security monitoring rule `type` property. See [#544](https://github.com/DataDog/datadog-api-client-python/pull/544).
+* [Added] Add `batch_id` to the synthetics trigger endpoint response. See [#556](https://github.com/DataDog/datadog-api-client-python/pull/556).
+* [Added] Add `audit alert` monitor type. See [#559](https://github.com/DataDog/datadog-api-client-python/pull/559).
+* [Added] Add DBM usage endpoint. See [#546](https://github.com/DataDog/datadog-api-client-python/pull/546).
+* [Added] Add config variables to Synthetics browser test config. See [#563](https://github.com/DataDog/datadog-api-client-python/pull/563).
+* [Added] Add `available_values` property to template variables schema. See [#564](https://github.com/DataDog/datadog-api-client-python/pull/564).
+* [Added] Add `follow_redirects` options to test request in Synthetics. See [#571](https://github.com/DataDog/datadog-api-client-python/pull/571).
+* [Fixed] Minor fixes of the incident schema. See [#552](https://github.com/DataDog/datadog-api-client-python/pull/552).
+* [Fixed] Make SLO history metadata unit nullable. See [#555](https://github.com/DataDog/datadog-api-client-python/pull/555).
+* [Fixed] Fix python unparsed serialization. See [#569](https://github.com/DataDog/datadog-api-client-python/pull/569).
+* [Fixed] Fix SLO history error response type for overall errors. See [#570](https://github.com/DataDog/datadog-api-client-python/pull/570).
+* [Changed] Fix SLO history schema for groups and monitors fields. See [#575](https://github.com/DataDog/datadog-api-client-python/pull/575).
+* [Changed] Remove metadata from required list for metric SLO history endpoint. See [#579](https://github.com/DataDog/datadog-api-client-python/pull/579).
+
 ## 1.3.0 / 2021-08-16
 
 * [Added] Add Webhooks integration support. See [#549](https://github.com/DataDog/datadog-api-client-python/pull/549).