Added 8.3 job in CI

Author: ezimuel

.ci/jobs/elastic+elasticsearch-php+8.3.yml

@@ -0,0 +1,14 @@
+---
+- job:
+    name: elastic+elasticsearch-php+8.3
+    display-name: 'elastic / elasticsearch-php # 8.3'
+    description: Testing the elasticsearch-php 8.3 branch.
+    parameters:
+    - string:
+        name: branch_specifier
+        default: refs/heads/8.3
+        description: the Git branch specifier to build (<branchName>, <tagName>,
+          <commitId>, etc.)
+    triggers:
+    - github
+    - timed: 'H */12 * * *'