Add type RepositoryAttachment for GetRepositoriesForCodeSecurityConfiguration

[ericmortebidbax]

As mentioned in my comment under #3217 there is a problem with the way GetRepositoriesForCodeSecurityConfiguration unmarshales the API result data. This PR fixes that particular problem.

It does not necessarily fix the original issue as reported.

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[ericmort]

This is a duplicate of #3707, this PR should be closed.

[gmlewis]

This is a duplicate of #3707, this PR should be closed.

OK, thank you, @ericmort!
Unfortunately, I can't close it yet but will hopefully get write access to this repo soon.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.08%. Comparing base (f137c94) to head (f3c6809).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #3705 +/- ##
=======================================
Coverage 91.08% 91.08% =======================================
Files 187 187 Lines 16581 16581 =======================================
Hits 15103 15103 Misses 1293 1293 Partials 185 185 

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[gmlewis]

This is a duplicate of #3707, this PR should be closed.

Closing.