[FIX] qweb: t-key in t-foreach is mandatory, throws otherwise

tests/qweb/__snapshots__/parser.test.ts.snap

@@ -0,0 +1,3 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`qweb parser simple t-foreach expression, t-key mandatory 1`] = `"\\"Directive t-foreach should always be used with a t-key!\\" (expression: t-foreach=\\"list\\" t-as=\\"item\\")"`;