Use condition instead of deprecated inline filter

I also faced this issue when I tried to create an Accordion Block.

I applied patch #5, and it solved the issue.

AaronChristian → closed merge request !15

I noticed that with the `if`, the `loop.index` wasn't counting correctly, so I changed it to use the `filter` filter instead.

Here is one example, the first accordion item should be open by default. With the `if` approach, it wasn't.

Using `filter`:

Moving it back to `Needs Review`.

Ahhh nice catch @ tpzurdo.

Thanks @carolpettirossi and @hfernandes, yep confirmed that this morning.

Thanks for the contributions back everyone.

Marking as RTBC, and I'll get this one merged into dev as well.