Update openpolicyagent/opa Docker tag to v1.18.2 (#1788)

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

Author: renovate[bot]

dependencies.Dockerfile

@@ -6,7 +6,7 @@
 FROM otel/weaver:v0.24.2@sha256:d1fb16d279f39810c340fbbf1cf9e5e995a3a9cefa531938e9012437e3bc00c1 AS weaver
 
 # OPA is used to test policies enforced by weaver.
-FROM openpolicyagent/opa:1.18.1@sha256:fffa40071c12b8da84518387ed5d7207322d74b04689aa3533e0ebe1e57666d5 AS opa
+FROM openpolicyagent/opa:1.18.2@sha256:cba27d3c6af2feba1e4d6e6b5e24df5b53db332420d4148a90acccd12efae6ed AS opa
 
 # Semconv gen is used for backwards compatibility checks.
 # TODO(jsuereth): Remove this when no longer used.