fix(stock): group get_picked_batches by batch and warehouse

get_picked_batches summed Serial-and-Batch-Entry qty while selecting bare
batch_no and warehouse with no GROUP BY. PostgreSQL rejects this outright:

    column "tabSerial and Batch Entry.batch_no" must appear in the GROUP BY clause

MariaDB does not error but collapses every picked row into a single result -
the grand-total qty pinned to one arbitrary batch - so the caller, which keys
the result by (batch_no, warehouse) to subtract already-picked stock, under-counts
whenever more than one batch is picked.

Add GROUP BY batch_no, warehouse so the query returns one correct row per batch
on both engines (this corrects the MariaDB result, not just Postgres validity).

erpnext/stock/doctype/serial_and_batch_bundle/serial_and_batch_bundle.py

@@ -3198,6 +3198,7 @@ def get_picked_batches(kwargs) -> dict[str, dict]:
 			& (table.voucher_type == "Pick List")
 			& (table.voucher_no.isnotnull())
 		)
+		.groupby(child_table.batch_no, child_table.warehouse)
 	)
 
 	if kwargs.get("company"):

erpnext/stock/doctype/serial_and_batch_bundle/test_serial_and_batch_bundle.py

@@ -1355,6 +1355,15 @@ class TestSerialandBatchBundle(ERPNextTestSuite):
 		# Stock queue should have the returned stock: [[5, 100]]
 		self.assertEqual(json.loads(return_sle.stock_queue), [[5, 100]])
 
+	def test_get_picked_batches_runs(self):
+		from erpnext.stock.doctype.serial_and_batch_bundle.serial_and_batch_bundle import get_picked_batches
+
+		# Sum(qty) is selected with bare batch_no/warehouse; without a GROUP BY this
+		# raises a GroupingError on Postgres (and collapses to one arbitrary row on
+		# MariaDB). It must run and return a per-(batch, warehouse) mapping on both.
+		result = get_picked_batches(frappe._dict())
+		self.assertIsInstance(result, dict)
+
 
 def get_batch_from_bundle(bundle):
 	from erpnext.stock.serial_batch_bundle import get_batch_nos