[conda] Completely remove "license_file" entry on conda recipe

See bob.devtools#44 and bob.devtools!127
4 jobs for fix_conda_license_file_issue in 3 minutes and 17 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #181226
docker
build_linux_36

00:02:42

73.0%
passed #181227
docker
build_linux_37

00:02:43

73.0%
passed #181224
macosx
build_macosx_36

00:02:37

73.0%
passed #181225
macosx
build_macosx_37

00:03:17

73.0%