fix: preserve schema 15 compatibility for v0.1.8

tests/test_monthly_settlement_navigation.py

@@ -69,6 +69,10 @@ class _FakeStreamlit:
     def popover(self, *args, **kwargs):
         return self._Column()
 
+    def link_button(self, label, url, **kwargs):
+        self.buttons.append((label, {"url": url, **kwargs}))
+        return False
+
     def rerun(self):
         return None