How change to the deveopment version of Lensfun

You are not advised to use the development version of lensfun (or version 0.3.95, which is not an official release) due to incompatibilities between the versions. See https://github.com/darktable-org/darktable/issues/2813 for details. Until this is resolved you are advised to stick to lensfun 0.3.2 and use the update facility to add lenses.