chore(deps): update ecr-scan-results-buildkite-plugin to v1.4.0

Key features of the newest version allows for vulnerability findings to be
ignored using repository local configuration, CVE lists are now sorted by
severity and score, and CVSS3 scores present in source feed are now displayed.

Full details in the release on GitHub.

See https://github.com/cultureamp/ecr-scan-results-buildkite-plugin/releases

README.md

@@ -48,7 +48,7 @@ steps:
   - command: "command which creates an image"
     # the docker-compose plugin may be used here instead of a command
     plugins:
-      - cultureamp/ecr-scan-results#v1.2.0:
+      - cultureamp/ecr-scan-results#v1.4.0:
           image-name: "$BUILD_REPO:deploy-$BUILD_TAG"
 ```
 
@@ -63,7 +63,7 @@ steps:
     plugins:
       - cultureamp/aws-assume-role:
           role: ${BUILD_ROLE}
-      - cultureamp/ecr-scan-results#v1.2.0:
+      - cultureamp/ecr-scan-results#v1.4.0:
           image-name: "$BUILD_REPO:deploy-$BUILD_TAG"
 ```
 
@@ -81,7 +81,7 @@ steps:
     plugins:
       - cultureamp/aws-assume-role:
           role: ${BUILD_ROLE}
-      - cultureamp/ecr-scan-results#v1.2.0:
+      - cultureamp/ecr-scan-results#v1.4.0:
           image-name: "$BUILD_REPO:deploy-$BUILD_TAG"
           max-criticals: "1"
           max-highs: "10"