Elastic Agent: Fix ECS fields resolution (#4007)

* Elastic Agent: Fix ECS fields resolution

* Update PR number in the changelog

Author: aleksmaus

packages/elastic_agent/_dev/build/build.yml

@@ -0,0 +1,3 @@
+dependencies:
+  ecs:
+    reference: [email protected]

packages/elastic_agent/changelog.yml

@@ -1,4 +1,9 @@
 # newer versions go on top
+- version: "1.3.5"
+  changes:
+    - description: Fix the external ECS fields not being properly resolved during the package build
+      type: bugfix
+      link: https://github.com/elastic/integrations/pull/4007
 - version: "1.3.4"
   changes:
     - description: Cloudbeat logs search support

packages/elastic_agent/manifest.yml

@@ -1,6 +1,6 @@
 name: elastic_agent
 title: Elastic Agent
-version: 1.3.4
+version: 1.3.5
 release: ga
 description: Collect logs and metrics from Elastic Agents.
 type: integration