319.fix.md

• Fixed ScmRun.groupby raising TypeError: Cannot interpret '<StringDtype(...)>' as a data type on Python 3.12 with pandas 3.x and numpy 2.x. Under the newer stack, string-valued meta columns can be pandas.StringDtype rather than object, and np.issubdtype rejects StringDtype as a non-coercible dtype. The numeric-dtype check inside RunGroupBy.__init__ is now routed through a try/except wrapper that returns False for any dtype numpy cannot classify, which is the semantically correct fallback. Unblocks downstream callers of ScmRun.convert_unit (and other groupby-using methods) on the newer Python / numpy / pandas stack.