The ruby bindings are not currently installable. We can reproduce this
with a build from source:
```
foundationdb/tmp on main [$?] via △ v3.25.2
zsh ❯ gem install ./bindings/ruby/fdb-7.3.0.gem
ERROR: While executing gem ... (Gem::Package::PathError)
installing into parent path /Users/andrew/projects/foundationdb/LICENSE of /Users/andrew/.rbenv/versions/3.2.1/lib/ruby/gems/3.2.0/gems/fdb-7.3.0 is not allowed
```
The problem is that the gemspec is interpolating the source directory
into the `files` array - and while this allows the gem to build, it
prevents it from actually being installed.
To fix it, we borrow similar code from the python bindings to copy the
necessary files and license into the build directory before building the
gem. This allows the gem to be installed:
```
foundationdb/tmp on main [!?] via △ v3.25.2
zsh ❯ gem install ./bindings/ruby/fdb-7.3.0.gem
Successfully installed fdb-7.3.0
Parsing documentation for fdb-7.3.0
Installing ri documentation for fdb-7.3.0
Done installing documentation for fdb after 0 seconds
1 gem installed
```
