Update recipe

There have been some updates on the conda-forge recipe since we tried it, including some changes to the build string. I am not sure if it has any impact on the package's hashes problem that we had, but it build working packages locally. Can we try it in the CI ?

The build of conda/bob-devel if failing due to conda conflicts caused by the faulty opencv packages. I think it should be solved when working opencv packages are pushed to bob's channel.