Convert tests to use mocks

[Teester]

Fixes #53.

Converts tests from using live wikidata data to using mocked data. This means changes in wikidata schemas and entities wont affect these tests. Additionally, running the tests is much quicker.

[codecov]

Codecov Report

❌ Patch coverage is 97.31544% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.75%. Comparing base (b428fe3) to head (0d70994).
⚠️ Report is 10 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
tests/tests_api_v2/test_jsonld.py	95.12%	2 Missing ⚠️
tests/tests_api_v2/test_schemas.py	95.23%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #92      +/-   ##
==========================================
- Coverage   92.38%   91.75%   -0.64%     
==========================================
  Files          17       17              
  Lines        1445     1588     +143     
==========================================
+ Hits         1335     1457     +122     
- Misses        110      131      +21     

Files with missing lines	Coverage Δ
tests/tests_api_v1/test_v1.py	88.46% <100.00%> (+3.92%)	⬆️
tests/tests_api_v2/test_compare_v1_v2.py	90.66% <100.00%> (+2.23%)	⬆️
tests/tests_api_v2/test_jsonld.py	96.62% <95.12%> (-1.29%)	⬇️
tests/tests_api_v2/test_schemas.py	89.50% <95.23%> (+1.55%)	⬆️

... and 4 files with indirect coverage changes

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[sonarqubecloud]

Quality Gate failed

Failed conditions
17.4% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud