Remove duplicate packages, which are in upstream
In this PR, I'm removing two packages:
-
python-stem ( https://github.com/openwrt/packages/pull/11156 ) -
python-jsonschema ( https://github.com/openwrt/packages/pull/11365 ) Jsonschema is required by Foris and it needs to be included in OpenWrt 19.07 and before/after merging this pull request, there needs to be created another pull request in turris-build to add those packages back as patches.