[fix] drop 'idna' from requirements.txt
Requirement idna was added in 181c12ae04ba but I don't know why. This package
is not directly used by searxng but its a sub-requirement of some other packages
using package `requests` (with different range of supported versions, see
below). In summary one can say: the version of idna should be depend on package
`requests`::
...
Pallets-Sphinx-Themes==1.2.3
...
- Sphinx [required: Any, installed: 3.5.4]
...
- requests [required: >=2.5.0, installed: 2.25.1]
...
- idna [required: >=2.5,<3, installed: 2.10]
...
...
transifex-client==0.14.2
- requests [required: >=2.19.1,<3.0.0, installed: 2.25.1]
...
- idna [required: >=2.5,<3, installed: 2.10]
twine==3.4.1
...
- requests [required: >=2.20, installed: 2.25.1]
...
- idna [required: >=2.5,<3, installed: 2.10]
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
Markus Heiser