fix: Use SchemaLoader instead of pyfilereader

pyfilereader was an old alias for SchemaLoader. Let's remove it. (it has been
removed from yams)
8 jobs for topic/default/fix_import in 29 minutes and 58 seconds (queued for 21 seconds)
Status Job ID Name Coverage
  Lint
passed lint_doc #28748

00:03:14

passed lint_doc8 #28747

00:02:00

passed lint_manifest #28746

00:02:01

passed lint_py #28745

00:01:54

 
  Tests
failed py3-from-forge #28752

00:03:53

failed py3_misc #28751

00:17:09

failed py3_server #28749

00:26:43

failed py3_web #28750

00:09:01

 
Name Stage Failure
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py3-from-forge Tests
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failed
py3_misc Tests
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py3_web Tests
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py3_server Tests
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