fix: Handle missing type value when checking JSON schema types

[edgarrmondragon]

Uncovered in MeltanoLabs/tap-dbt#119

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📚 Documentation preview 📚: https://meltano-sdk--1526.org.readthedocs.build/en/1526/

[codecov]

Codecov Report

Merging #1526 (128496a) into main (97b4906) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1526   +/-   ##
=======================================
  Coverage   85.50%   85.50%           
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  Files          57       57           
  Lines        4692     4692           
  Branches      802      802           
=======================================
  Hits         4012     4012           
  Misses        489      489           
  Partials      191      191           

Impacted Files	Coverage Δ
singer_sdk/helpers/_typing.py	74.19% <100.00%> (ø)

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[mjsqu]

Looks good, in the case we found in tap-dbt, this would loop over the "anyOf" list and skip past "enum" without returning anything but output True when encountering the "type" key. The test looks exactly like the case in tap-dbt. Great work @edgarrmondragon 👍