update WS

content/week_1_3/WS_1_3_Moving_Ice.ipynb

content/week_1_3/WS_1_3_solution.ipynb

src/students/Week_1_3/WS_1_3_Moving_Ice.html

src/students/Week_1_3/WS_1_3_Moving_Ice.ipynb

src/teachers/Week_1_3/WS_1_3_Moving_Ice.html

src/teachers/Week_1_3/WS_1_3_solution.html