Update ODBC driver version

Author: David-Engel

docs/connect/python/pyodbc/step-3-proof-of-concept-connecting-to-sql-using-pyodbc.md

@@ -33,7 +33,7 @@ server = 'tcp:myserver.database.windows.net'
 database = 'mydb' 
 username = 'myusername' 
 password = 'mypassword' 
-cnxn = pyodbc.connect('DRIVER={ODBC Driver 17 for SQL Server};SERVER='+server+';DATABASE='+database+';UID='+username+';PWD='+ password)
+cnxn = pyodbc.connect('DRIVER={ODBC Driver 18 for SQL Server};SERVER='+server+';DATABASE='+database+';UID='+username+';PWD='+ password)
 cursor = cnxn.cursor()
 
 ```