Update sympy from 0.7.4.1 to 1.13.1

Author: pyup-bot

requirements.txt

@@ -51,7 +51,7 @@ simpy==3.0.8
 six==1.6.1
 sqlalchemy==0.9.7
 sqlite3==2.6.0
-sympy==0.7.4.1
+sympy==1.13.1
 thrift
 turtle
 twitter==1.19.6