Bump the gradle-deps group with 3 updates

Bumps the gradle-deps group with 3 updates: [cd.go.plugin:go-plugin-api](https://github.com/gocd/gocd), [org.apache.commons:commons-exec](https://github.com/apache/commons-exec) and [org.mockito:mockito-junit-jupiter](https://github.com/mockito/mockito).


Updates `cd.go.plugin:go-plugin-api` from 25.3.0 to 25.4.0
- [Release notes](https://github.com/gocd/gocd/releases)
- [Commits](gocd/gocd@25.3.0...25.4.0)

Updates `org.apache.commons:commons-exec` from 1.5.0 to 1.6.0
- [Changelog](https://github.com/apache/commons-exec/blob/master/RELEASE-NOTES.txt)
- [Commits](apache/commons-exec@rel/commons-exec-1.5.0...rel/commons-exec-1.6.0)

Updates `org.mockito:mockito-junit-jupiter` from 5.20.0 to 5.21.0
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v5.20.0...v5.21.0)

---
updated-dependencies:
- dependency-name: cd.go.plugin:go-plugin-api
  dependency-version: 25.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: gradle-deps
- dependency-name: org.apache.commons:commons-exec
  dependency-version: 1.6.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: gradle-deps
- dependency-name: org.mockito:mockito-junit-jupiter
  dependency-version: 5.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: gradle-deps
...

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

Author: dependabot[bot]

build.gradle

@@ -48,14 +48,14 @@ repositories {
 }
 
 ext {
-    gocdPluginVersion = '25.3.0'
+    gocdPluginVersion = '25.4.0'
 }
 
 dependencies {
     compileOnly "cd.go.plugin:go-plugin-api:${gocdPluginVersion}"
 
     implementation 'joda-time:joda-time:2.14.0'
-    implementation 'org.apache.commons:commons-exec:1.5.0'
+    implementation 'org.apache.commons:commons-exec:1.6.0'
     implementation 'commons-io:commons-io:2.21.0'
 
     implementation platform('com.fasterxml.jackson:jackson-bom:2.20.1')
@@ -68,7 +68,7 @@ dependencies {
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine'
     testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
     testCompileOnly "cd.go.plugin:go-plugin-api:${gocdPluginVersion}"
-    testImplementation 'org.mockito:mockito-junit-jupiter:5.20.0'
+    testImplementation 'org.mockito:mockito-junit-jupiter:5.21.0'
     testImplementation 'org.assertj:assertj-core:3.27.6'
     testImplementation 'uk.org.webcompere:system-stubs-jupiter:2.1.8'
 }