feat: Update to OPA v1.2.0 (#373)

Regorus now defaults to rego v1. `import rego.v1` is no longer needed.
Additionally, `future` keywords are automatically imported.

See
https://www.openpolicyagent.org/docs/latest/v0-upgrade/#changes-to-rego-in-opa-v10
to understand the differences between rego v1 and v0.

BREAKING CHANGE:

v0 style policies will error out by default. To enable v0 behavior, call engine.set_rego_v0(true) before
loading policies.

Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>

bindings/c/main.c

@@ -6,6 +6,11 @@ int main() {
     RegorusEngine* engine = regorus_engine_new();
     RegorusResult r;
 
+    // Turn on rego v0 since policy uses v0.
+    r = regorus_engine_set_rego_v0(engine, true);
+    if (r.status != RegorusStatusOk)
+	goto error;
+
     // Load policies.
     r = regorus_engine_add_policy_from_file(engine, "../../../tests/aci/framework.rego");
     if (r.status != RegorusStatusOk)