GPG Pinentry inside TMUX

See it in action:

Installation

add your fallback pinentry to pinentry-tmux.sh
put the shell script in your path, eg. ~/.local/bin/pinentry-tmux (without .sh)
configure gpg to use pinentry-tmux for pinentry
for the script to detect that it’s running inside of TMUX, add this to your TMUX config:
```
PINENTRY_USER_DATA="tmux"
```