Spring Upgrade to Gradle 7.6

Includes build support for JDK 19.

Comment From: vpavic

Note that some Gradle releases (and 7.6 is one of those) also update wrapper scripts and/or wrapper binary. So it's necessary to run ./gradlew wrapper after bumping the Gradle version in gradle-wrapper.properties, in order for those files to self-update.

Comment From: sbrannen

Updated wrapper in 902f8dd1d8350bc7fbdf711fa92a8a01fd5d0036