Upgrade OPA and regal to latest versions

policies/.regal/config.yaml

@@ -4,6 +4,9 @@
 # Please see LICENSE files in the repository root for full details.
 
 rules:
+  imports:
+    unresolved-reference:
+      level: ignore
   style:
     external-reference:
       level: ignore

policies/Makefile

@@ -6,8 +6,10 @@
 # Set to 1 to run OPA through Docker
 DOCKER := 0
 PODMAN := 0
-OPA_DOCKER_IMAGE := docker.io/openpolicyagent/opa:1.1.0-debug
-REGAL_DOCKER_IMAGE := ghcr.io/styrainc/regal:0.31.0
+# Keep in sync with Dockerfile and .github/actions/build-policies/action.yml
+OPA_DOCKER_IMAGE := docker.io/openpolicyagent/opa:1.8.0-debug
+# Keep in sync with .github/workflows/ci.yaml
+REGAL_DOCKER_IMAGE := ghcr.io/styrainc/regal:0.36.1
 
 INPUTS := \
 	common/common.rego \