Bump rsolr from 2.3.0 to 2.4.0

Bumps rsolr from 2.3.0 to 2.4.0.

Changelog

Sourced from rsolr's changelog.

2.4.0

• Raise specific timeout error for solr timeouts. https://github.com/rsolr/rsolr/pull/214
• Pass timeout RSolr configuration through to Faraday, deprecate read_timeout Rsolr configuration. https://github.com/rsolr/rsolr/pull/215
• Better visibility of Solr error message in RSolr::Error. https://github.com/rsolr/rsolr/pull/222
• Add soft-commit function https://github.com/rsolr/rsolr/pull/210 (thanks @giteshnandre)
• Avoid encoding exception in error message display https://github.com/rsolr/rsolr/pull/208 (thanks @expajp)
• Fix JSON generator for atomic updates of array fields https://github.com/rsolr/rsolr/pull/201 (thanks @serggl)

Commits

• 97e3d37 Merge pull request #223 from rsolr/prepare_for_2.4.0_release
• f0a352c prepare for RSolr 2.4.0 release
• e10ce01 Merge pull request #227 from rsolr/avoid_deprecated_read_timeout_in_tests
• 25a3bf0 Merge pull request #201 from serggl/bugfix/200
• ce03d38 Avoid using deprecated read_timeout in tests
• 0f2ce40 Merge pull request #226 from rsolr/guard_nil_response
• 1f543fa guard against nil response
• 5ea30b8 bugfix: failure of generating errorlogs when a response body includes multiby...
• 149afb5 Add soft-commit function (#210)
• bc7f6e2 Merge pull request #222 from rsolr/extract_solr_error_from_json
• Additional commits viewable in compare view