feat: add endpoints to fetch gradecard and cgpa

[SohamKukreti]

zoo wee mama

code i used to test:

import wrapper as wp
from default import CAPTCHA

w = wp.Webportal()

s = w.student_login("username", "password", CAPTCHA)

semesters = w.get_semesters_for_grade_card()

gradecard = w.get_grade_card(semesters[0])

print(gradecard, end = "\n\n\n")

sgpa_cgpa = w.get_sgpa_cgpa()

print(sgpa_cgpa)

lemme know if i need to change something