Fix a typo in branchname assignment

Author: aaruni96

tester.py

@@ -5,7 +5,7 @@
 print(sys.argv)
 
 repo = f"{sys.argv[1]}/{sys.argv[2]}"
-branch = {sys.argv[3]}
+branch = sys.argv[3]
 filename = sys.argv[4]
 tut = f'''https://raw.githubusercontent.com/{repo}/{branch}/{filename}.ipynb'''
 nbfilename = f"notebooks/{filename}.ipynb"