fix: Update xsection.py

- remove 13TeV xsection
- Changes made to the xsec in consistent to BTV private google sheeet:
https://docs.google.com/spreadsheets/d/1WUwRG6b6iiPSUr-bDyLjSA4JW8ePdsY3Q55J7gSq4gc/edit

src/BTVNanoCommissioning/helpers/xs_scaler.py

@@ -3,6 +3,8 @@
 from coffea.processor import accumulate
 import os
 from BTVNanoCommissioning.helpers.xsection import xsection
+
+# from BTVNanoCommissioning.helpers.xsection_13TeV import xsection_13TeV
 import numpy as np
 
 
@@ -44,7 +46,10 @@ def scaleSumW(output, lumi):
                     if ("data" in sample) or ("Run" in sample) or ("Double" in sample):
                         h = h
                     else:
-                        raise KeyError(sample, "is not found in xsection.py")
+                        raise KeyError(
+                            sample,
+                            "is not found in xsection.py. If you're using 13TeV samples, please use xsection_13TeV.py",
+                        )
 
                 scaled[sample][key] = h
     return scaled