Update buildkite plugin secrets to v2

Author: renovate[bot]

.buildkite/pipeline.yml

@@ -30,7 +30,7 @@ steps:
   - label: "Security Scan"
     key: security_scan
     plugins:
-      - secrets#v1.0.2:
+      - secrets#v2.0.0:
           variables:
             GITHUB_TOKEN: GITHUB_TOKEN
       - ossf-scorecard#v1.0.1: