Python 3 compatibility syntax error fixes (#10519)

* Use Python 3 style print function

* Use 'Exception as e' instead of 'Exception, e'

* Unpack tuple arguments explicitly in instead of relying on auto unpacking

* Use consistent indentation

* Use 0 if stock_frozen_upto_days is None
diff --git a/erpnext/schools/api.py b/erpnext/schools/api.py
index c613c8c..ff2da07 100644
--- a/erpnext/schools/api.py
+++ b/erpnext/schools/api.py
@@ -63,7 +63,7 @@
 	:param student_group: Student Group.
 	:param date: Date.
 	"""
-	 
+
 	present = json.loads(students_present)
 	absent = json.loads(students_absent)