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>

tests/aci/main.rs

@@ -27,6 +27,7 @@ struct YamlTest {
 
 fn eval_test_case(dir: &Path, case: &TestCase) -> Result<Value> {
     let mut engine = Engine::new();
+    engine.set_rego_v0(true);
 
     engine.add_data(case.data.clone())?;
     engine.set_input(case.input.clone());
@@ -116,6 +117,7 @@ fn run_aci_tests(dir: &Path) -> Result<()> {
 #[cfg(feature = "coverage")]
 fn run_aci_tests_coverage(dir: &Path) -> Result<()> {
     let mut engine = Engine::new();
+    engine.set_rego_v0(true);
     engine.set_enable_coverage(true);
 
     let mut added = std::collections::BTreeSet::new();