Update OSCAL submodule to v1.2.3

[selenaxiao-nist]

Committer Notes

Updates OSCAL submodule to v1.2.3

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### Changes to Core Features:

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[selenaxiao-nist]

Tested build locally. Not a breaking change in liboscal-java or oscal-cli

[iMichaela]

Builds correctly with OSCAL 1.2.3