feat: Added Week7 and Week8 tasks

Week7_8/array_slicing.py

Week7_8/excluded.py

Week7_8/fivexfive.py

Week7_8/identity.py

Week7_8/null_vector.py

Week7_8/pandas_arithmetic.py

Week7_8/random_arrayreshape.py

Week7_8/random_shape.py

Week7_8/table_panda.py

Week7_8/tabledf.csv

Week7_8/week7_8.docx