Made some changes to metrics.py. Added a new metrics called "InventoryQuantityPerCumulativePower" to return the explicit inventory table with quantity in units of kg/GWe, calculated by dividing the original quantity by the cumulative sum of the electricity generated in TimeSeriesPower metric from time 0 and created the test to check the expected output as well. Feel free to give feedback or suggestions :).
Merging prerequisite: PR #164
Made some changes to metrics.py. Added a new metrics called "InventoryQuantityPerCumulativePower" to return the explicit inventory table with quantity in units of kg/GWe, calculated by dividing the original quantity by the cumulative sum of the electricity generated in TimeSeriesPower metric from time 0 and created the test to check the expected output as well. Feel free to give feedback or suggestions :).