Make usage message in pipx run show package_or_url

[dukecat0]

• I have added an entry to docs/changelog.md

Summary of changes

Make usage message in pipx run show package_or_url instead of package_name

Before:

$ pipx run pymodbus[repl]
'pymodbus' executable script not found in package 'pymodbus'.
Available executable scripts:
    pymodbus.console - usage: 'pipx run --spec pymodbus pymodbus.console [arguments?]'
    pymodbus.server - usage: 'pipx run --spec pymodbus pymodbus.server [arguments?]'
    pymodbus.simulator - usage: 'pipx run --spec pymodbus pymodbus.simulator [arguments?]'

After:

$ pipx run pymodbus[repl]
'pymodbus' executable script not found in package 'pymodbus'.
Available executable scripts:
    pymodbus.console - usage: 'pipx run --spec pymodbus[repl] pymodbus.console [arguments?]'
    pymodbus.server - usage: 'pipx run --spec pymodbus[repl] pymodbus.server [arguments?]'
    pymodbus.simulator - usage: 'pipx run --spec pymodbus[repl] pymodbus.simulator [arguments?]'