ref-doc: Spring Boot version overrides project dependency in examples

[sjohnr]

The project dependency in spring-authorization-server-docs-examples.gradle resolves to Spring Boot's managed version since 3.1.0-RC1:

spring-authorization-server/docs/src/docs/asciidoc/examples/spring-authorization-server-docs-examples.gradle

Line 15 in 878a75d

implementation platform("org.springframework.boot:spring-boot-dependencies:3.1.0-RC1")

spring-authorization-server-docs-examples should resolve the internal project dependency when using:

implementation project(":spring-security-oauth2-authorization-server")