acts_as_indexed

Thanks to Ryan Kopf for reviewing PRs, fixing the broken CI, and tidying things up to make this release possible.

• Now tested on Ruby 3.0 and Ruby 3.1. #70. [ryankopf - Ryan Kopf]
• Remove deprecated Fixnum references. #62. [yez - Jake Yesbeck]
• Delete Gemfile.lock from repo. #68. [parndt - Philip Arndt]
• Bump i18n from 0.6.1 to 0.9.5. #64
• Bump tzinfo from 0.3.35 to 0.3.61. #66
• Bump will_paginate from 3.0.3 to 3.0.5. #67