Filter collection trading volumes by marketplace

We added a marketplace parameter to our [collection volume](https://docs.center.dev/reference/getcollectionvolume-v2) endpoint that allows users to filter for volume from specific marketplaces. We support OpenSea and Blur so far, with more to come!

We added a marketplace parameter to our collection volume endpoint that allows users to filter for volume from specific marketplaces. We support OpenSea and Blur so far, with more to come!