Remove legacy configuration

[cherylking]

Support for Gradle 8 was added in our 3.6 release. The following messages appear frequently in the console.

The configuration :classpath is both resolvable and consumable. This is considered a legacy configuration and it will eventually only be possible to be one of these.
The configuration :classpath is both consumable and declarable. This combination is incorrect, only one of these flags should be set.

The configuration :mainSourceElements is both consumable and declarable. This combination is incorrect, only one of these flags should be set.
The configuration :signatures is both resolvable and consumable. This is considered a legacy configuration and it will eventually only be possible to be one of these.
The configuration :signatures is both consumable and declarable. This combination is incorrect, only one of these flags should be set.

The configuration detachedConfiguration1 is both resolvable and consumable. This is considered a legacy configuration and it will eventually only be possible to be one of these.
The configuration :detachedConfiguration1 is both consumable and declarable. This combination is incorrect, only one of these flags should be set.

[cherylking]

This may just be a bug in Gradle 8.0/8.1. It was supposedly fixed in 8.1, but someone else reported still seeing it. I also ran with 8.1.1 when I saw these messages.