can't install on old fedora

can't install on Fedora (pretty old one (35), but still)

I am missing the `shasum` binary that's required by the installation script. I have `sha1sum` binary present, but it has slightly different contract, so that even if I alias or symlink the shasum -> sha1sum, it can't pass the followin check:

```
shasum -v 1>/dev/null 2>&1 || (echo "Missing shasum binary" && exit 1)
```
(which is present in your install script)

sha1sum uses either `sha1sum --version` or `sha1sum --v`

```
sha1sum --v
sha1sum (GNU coreutils) 8.32
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later .
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

sha1sum -v
sha1sum: invalid option -- 'v'
Try 'sha1sum --help' for more information.
```

I'd contribute and make the script working, but it can't be found in this repo.

<3