Update catalog, add cli access to refresh, make rdflib optional

[rlskoeser]

Associated Issue: #7

Changes in this PR

• update catalog list of schemas and regenerate
• make refresh catalog runnable as cli script
• make rdflib an optional dependency
  • add rdflib as an option in github test matrix
• add dc types rdf file to catalog and reference there

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (develop@701d20f). Learn more about missing BASE report.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop      #23   +/-   ##
==========================================
  Coverage           ?   85.80%           
==========================================
  Files              ?       15           
  Lines              ?     2170           
  Branches           ?        0           
==========================================
  Hits               ?     1862           
  Misses             ?      308           
  Partials           ?        0           

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.