Add a release-only test for `is_active()` behavior

tests/inactive_release.rs

@@ -0,0 +1,10 @@
+use qadapt::QADAPT;
+
+#[global_allocator]
+static Q: QADAPT = QADAPT;
+
+#[cfg(not(debug_assertions))]
+#[test]
+fn release_only_inactive() {
+    assert!(!qadapt::is_active());
+}