2.1.2: fixes a deprecation warning in python 3.13

Author: kaelzhang

.github/workflows/python.yml

@@ -9,7 +9,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: [3.9, 3.12]
+        python-version: [3.9, 3.13]
 
     steps:
     - uses: actions/checkout@v4

stock_pandas/__init__.py

@@ -20,4 +20,4 @@
     cumulators
 )
 
-__version__ = '2.1.1'
+__version__ = '2.1.2'

stock_pandas/meta/time_frame.py

@@ -88,7 +88,7 @@ def define(
     primary_name = names[0]
 
     class NewClass(TimeFrame):
-        _unify = unify
+        _unify = staticmethod(unify)
         _str = primary_name
 
     NewClass.__name__ = f'TimeFrame{suffix}'