Statutory citation filter broken

[patphongs]

When performing a filter for statutory citations, the API returns a 500 error. Citation filters were just added back into the AO search here: https://fec-dev-proxy.app.cloud.gov/data/legal/search/advisory-opinions/?type=advisory_opinions&ao_category=F

Here's an example of the API error when attempting to filter by statutory citation: https://fec-dev-api.app.cloud.gov/v1/legal/search/?type=advisory_opinions&ao_category=F&ao_statutory_citation=52+U.S.C.+%C2%A730101

[vrajmohan]

This is an easy fix. @AmyKort, should we expedite the fix so that it makes the release slated for Sep 11?

[AmyKort]

That would be perfect if we can make it work @vrajmohan Thank you so much!

[vrajmohan]

Done. Thanks, @lbeaufort, for retargeting my PR.