Bech32 private keys

It is now possible to use bech32 format (nsec1...) when configuring bot's private key.

Shorten subscription ID

• Shorten subscription ID which is send in "REQ" message (from 64 characters to 32, some relays refused the subscription request with the longer one)
• A bit of code cleanups

"Feature" Fix

• Commands were executed consecutively instead of using tokio's task system.

Another Bugfix

• Fix subscription (limit it correctly to kind 1 events)

Bugfix

• Fix pongs being treated as a string messages
• Small doc update + code formatting

Couple of Improvements

• Events validity is checked, if the ID is incorrect or the signature is invalid, the event is ignored
• Improved documentation
• Responding to pings with pongs
• Due to issues with relays disconnection, the pings are send every 30 seconds to every relay to keep the connection alive
• Using GitHub Actions to run the two unit tests that were added and also running cargo clippy

First Release

Contains basic stuff needed for writing a nostr bot.