Remove unneeded exec bits from some files

I noticed that some files in rubygems were executable, and I could think
of no reason why they should be.

In general, I think ruby files should never have the executable bit set
unless they include a shebang, so I run the following command over the
whole repo:

```bash
find . -name '*.rb' -type f -executable -exec bash -c 'grep -L "^#!" $1 || chmod -x $1' _ {} \;
```

1 files changed, 0 insertions, 0 deletions

diff --git a/test/csv/test_data_converters.rb b/test/csv/test_data_converters.rb
index 1620e077be..1620e077be 100755..100644
--- a/test/csv/test_data_converters.rb
+++ b/test/csv/test_data_converters.rb