feat: add force of gravity kata and its test-function

src/codewars/kata_force_of_gravity.py

@@ -0,0 +1,5 @@
+# https://www.codewars.com/kata/5b609ebc8f47bd595e000627/
+
+
+def solution(arr_val, arr_unit):
+    pass

tests/codewars/test_kata_force_of_gravity.py

@@ -0,0 +1,6 @@
+from src.codewars.kata_force_of_gravity import solution
+
+def basic_test_cases():
+    assert solution([1000, 1000, 100], ["g", "kg", "m"]) == 6.67e-12
+    assert solution([1000, 1000, 100], ["kg", "kg", "m"]) == 6.667e-9
+    assert solution([1000, 1000, 100], ["kg", "kg", "cm"]) == 0.0000667