chore: Only run PR checks on pull_request (#116)

* Only test on pull_request
* Update CHANGELOG

Author: bgrant

.github/workflows/tests.yml

@@ -1,6 +1,6 @@
 name: unit-tests-and-static-analysis
 
-on: [push, pull_request]
+on: [pull_request]
 
 jobs:
   build:

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+# [unreleased] - XXXX-XX-XX
+### Changed
+- [PR 116](https://github.com/salesforce/django-declarative-apis/pull/XXX) Only run PR checks on `pull_request`
+
 # [0.25.2] - 2023-01-20
 ### Fixed
 - [PR 120](https://github.com/salesforce/django-declarative-apis/pull/120) Fix correlation ID logging for deferred tasks