PyJWT is a very brittle and cumbersome dependency that expects several
cryptography libraries to be already installed on the system, and it can
lead to hard-to-debug errors when ported to different systems.
Moreover, it installs the whole `cryptography` package, which is several
MBs in size, takes time to compile, and it requires a Rust compiler to
be present on the target machine.
Platypush will now use the Python-native `rsa` module to handle JWT
tokens.