Add v7.3.0 release in CHANGELOG.md

Author: jbern0rd

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 All notable changes to this project will be documented in this file.
 
+## [[7.3.0]](https://github.com/iExecBlockchainComputing/iexec-result-proxy/releases/tag/v7.3.0) 2023-01-18
+
+* Add health endpoint to allow health checks mechanism enablement.
+
 ## [[7.2.0]](https://github.com/iExecBlockchainComputing/iexec-result-proxy/releases/tag/v7.2.0) 2023-01-09
 
 * Increments jenkins-library up to version 2.2.3. Enable SonarCloud analyses on branches and pull requests.