libyang: support working with the decimal64 type

Change-Id: I3a36658fe810089970a99d71003124b3041ee6a0
diff --git a/tests/datastore_access.cpp b/tests/datastore_access.cpp
index 88b05c3..093f348 100644
--- a/tests/datastore_access.cpp
+++ b/tests/datastore_access.cpp
@@ -288,6 +288,17 @@
 
     }
 
+    SECTION("floats")
+    {
+        datastore.setLeaf("/example-schema:leafDecimal", 123.4);
+        REQUIRE_CALL(mock, write("/example-schema:leafDecimal", std::nullopt, "123.4"s));
+        datastore.commitChanges();
+        DatastoreAccess::Tree expected {
+            {"/example-schema:leafDecimal", 123.4},
+        };
+        REQUIRE(datastore.getItems("/example-schema:leafDecimal") == expected);
+    }
+
     waitForCompletionAndBitMore(seq1);
 }