Remove upstream pins for conda-forge-pinning packages

This MR removes upstream.yaml references to those packages that are pinned as part of conda-forge-pinning.

Those packages specified in conda-forge-pinning are (for the most part) SO libraries that use run_exports to pin dependents to specific version ranges for compatibility - if we specify a specific version in our upstream.yaml that just means we have to update things whenever conda-forge-pinning migrates from one version to another, working out which packages to update, and to which versions can be extremely time consuming. I trust the conda-forge team to know what they are doing, so removing our pins should just prevent some unnecessary conflicts when updating packages we actually care about.