Allow integration tests to use Spring Boot

- The integration-tests module uses SB dependencies
  for test setup. This is problematic when attempting
  a non-snapshot release as non-snapshot releases do
  not include `repos.spring.io/snapshot`. This commit
  treats the `integration-tests` module like the samples
  module and always includes central, milestone, and
  snapshot repos.

integration-tests/integration-tests.gradle

@@ -6,6 +6,12 @@ plugins {
 
 description = 'Spring Pulsar Integration Tests'
 
+repositories {
+	mavenCentral()
+	maven { url 'https://repo.spring.io/milestone' }
+	maven { url 'https://repo.spring.io/snapshot' }
+}
+
 dependencies {
 	intTestImplementation project(':spring-pulsar-test')
 	intTestRuntimeOnly 'ch.qos.logback:logback-classic'