publishStubsToScm fails with NoClassDefFoundError

[p-ssanders]

Describe the bug
With

• Spring Cloud Contract 2020.0.4
• Spring Boot 2.5.6
• spring-cloud-contract-gradle-plugin 3.0.4
• Gradle 7.3

publishStubsToScm gradle task fails when targeting a remote git repository with the error:

Caused by: java.lang.IllegalStateException: Exception occurred while cloning repo
	at org.springframework.cloud.contract.stubrunner.GitRepo.cloneProject(GitRepo.java:126)
...
Caused by: java.lang.NoClassDefFoundError: com/jcraft/jsch/agentproxy/connector/SSHAgentConnector
	at org.springframework.cloud.contract.stubrunner.GitRepo$JGitFactory$1.createDefaultJSch(GitRepo.java:339)

Sample
A project to reproduce this problem can be found at https://github.com/p-ssanders/scc-publishstubstoscm-example
Run ./gradlew clean build publishStubsToScm --stacktrace to reproduce