Update Gradle example to use latest plugin release
Update Gradle example to use latest plugin release

Uses fixed versions as `latest.release` no longer works with the Gradle Plugin Portal.
Also uses a fixed version for EP as a “best practice” to make the build reproducible.
davidzchen/error-prone,davidzchen/error-prone,cushon/error-prone,Anish2/error-prone,gnanam336/error-prone,gnanam336/error-prone,cushon/error-prone,cushon/error-prone,davidzchen/error-prone,gnanam336/error-prone,Turbo87/error-prone,google/error-prone,cushon/error-prone,Anish2/error-prone,Anish2/error-prone,google/error-prone,Turbo87/error-prone,davidzchen/error-prone,Turbo87/error-prone,Anish2/error-prone