[ruby] Pin RecordLoader to v0.3.0

[StephenHulme]

Pins RecordLoader to the current version while incoming upgrades are tested.

Requires sanger/record_loader#49 and sanger/record_loader#55

Changes proposed in this pull request

• Pin record_loader to v0.3.0

Instructions for Reviewers

[All PRs] - Confirm PR template filled
[Feature Branches] - Review code
[Production Merges to main]
    - Check story numbers included
    - Check for debug code
    - Check version

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.32%. Comparing base (1f2c353) to head (f58bbc3).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #5744   +/-   ##
========================================
  Coverage    87.32%   87.32%           
========================================
  Files         1476     1476           
  Lines        33517    33517           
  Branches      3549     3549           
========================================
  Hits         29270    29270           
  Misses        4226     4226           
  Partials        21       21           

Flag	Coverage Δ
javascript	50.00% <ø> (ø)
ruby	87.34% <ø> (+<0.01%)	⬆️

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