Update openpolicyagent/opa Docker tag to v1.6.0 (#2487)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

dependencies.Dockerfile

@@ -6,7 +6,7 @@
 FROM otel/weaver:v0.16.1@sha256:5ca4901b460217604ddb83feaca05238e2b016a226ecfb9b87a95555918a03af AS weaver
 
 # OPA is used to test policies enforced by weaver.
-FROM openpolicyagent/opa:1.5.1@sha256:7d30d984125161b7f30599c6bdf80a6f2301dbbd526725714c231aad8179e4b9 AS opa
+FROM openpolicyagent/opa:1.6.0@sha256:72220208128e960b6620c155630566a38b76de2d4f230c3ca9442aaaf6626077 AS opa
 
 # Lychee is used for checking links in documentation.
 FROM lycheeverse/lychee:sha-2aa22f8@sha256:2e3786630482c41f9f2dd081e06d7da1c36d66996e8cf6573409b8bc418d48c4 AS lychee