Drop, migrate old patches

• The patches for barbies, ghc-tcplugins-extra, ghc-typelits-extra, mono-traversable, and persistent-sqlite have all been dropped as their latest Hackage versions support GHC 8.8 through HEAD.
• The pandoc-2.9.1 patch has been migrated to support the latest Hackage version, 2.9.1.1.