Bump go-plugin-api from 20.10.0 to 21.1.0

Bumps [go-plugin-api](https://github.com/gocd/gocd) from 20.10.0 to 21.1.0.
- [Release notes](https://github.com/gocd/gocd/releases)
- [Commits](gocd/gocd@20.10.0...21.1.0)

Signed-off-by: dependabot-preview[bot] <[email protected]>

build.gradle

@@ -58,7 +58,7 @@ sourceSets {
 
 dependencies {
   compile group: 'cd.go.plugin.base', name: 'gocd-plugin-base', version: '0.0.1'
-  compileOnly group: 'cd.go.plugin', name: 'go-plugin-api', version: '20.10.0'
+  compileOnly group: 'cd.go.plugin', name: 'go-plugin-api', version: '21.1.0'
   compile group: 'com.google.code.gson', name: 'gson', version: '2.8.6'
   compile group: 'com.amazonaws', name: 'aws-java-sdk-secretsmanager', version: '1.11.931'
   compile group: 'com.amazonaws.secretsmanager', name: 'aws-secretsmanager-caching-java', version: '1.0.1'
@@ -69,7 +69,7 @@ dependencies {
   testCompile group: 'org.assertj', name: 'assertj-core', version: '3.18.1'
   testCompile group: 'org.mockito', name: 'mockito-core', version: '3.7.0'
   testCompile group: 'org.jsoup', name: 'jsoup', version: '1.13.1'
-  testCompile group: 'cd.go.plugin', name: 'go-plugin-api', version: '20.9.0'
+  testCompile group: 'cd.go.plugin', name: 'go-plugin-api', version: '21.1.0'
   testCompile group: 'org.skyscreamer', name: 'jsonassert', version: '1.5.0'
 }