Adding support for esbuild in the testing matrix

Following Blacklight's lead it would be nice to add support to for `esbuild` in blacklight-gallery's testing pipeline. Currently, the pipeline for esbuild fails with a [spec failure](https://github.com/projectblacklight/blacklight-gallery/actions/runs/15000253225/job/42145434525?pr=190#step:5:449).