fix: workaround for gradle 8+ dependency issues

[aajtodd]

Issue #, if available:
workaround for gradle/gradle#26091

Description of changes:
Workaround for Gradle 8.5 upgrade having issues with task dependencies and signing

FAILURE: Build failed with an exception.

* What went wrong:
A problem was found with the configuration of task ':bom:signVersionCatalogPublication' (type 'Sign').
  - Gradle detected a problem with the following location: '/codebuild/output/src1917448208/src/smithy-kotlin/bom/build/distributions/bom-1.0.5-javadoc.jar.asc'.
    
    Reason: Task ':bom:publishBomPublicationToTestLocalRepository' uses this output of task ':bom:signVersionCatalogPublication' without declaring an explicit or implicit dependency. This can lead to incorrect results being produced, depending on what order the tasks are executed.

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