chore(signature): swap order of arguments to compatible

Should be `implementation, interface_def`, not the other way around

Author: gforsyth

Diff for: ibis/backends/tests/test_signatures.py

@@ -23,4 +23,5 @@ def test_signatures(base_cls, method, backend_cls):
     base_sig = inspect.signature(getattr(base_cls, method))
     backend_sig = inspect.signature(getattr(backend_cls, method))
 
-    assert compatible(base_sig, backend_sig, check_annotations=False)
+    # Usage is compatible(implementation_signature, defined_interface_signature, ...)
+    assert compatible(backend_sig, base_sig, check_annotations=False)