Bump spock-core from 2.0-groovy-3.0 to 2.1-groovy-3.0 in /buildSrc

Bumps spock-core from 2.0-groovy-3.0 to 2.1-groovy-3.0.

---
updated-dependencies:
- dependency-name: org.spockframework:spock-core
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

buildSrc/build.gradle

@@ -124,7 +124,7 @@ dependencies {
   testFixturesApi gradleTestKit()
   testImplementation 'com.github.tomakehurst:wiremock-jre8-standalone:2.23.2'
   testImplementation "org.mockito:mockito-core:${props.getProperty('mockito')}"
-  integTestImplementation('org.spockframework:spock-core:2.0-groovy-3.0') {
+  integTestImplementation('org.spockframework:spock-core:2.1-groovy-3.0') {
     exclude module: "groovy"
   }
 }