Bump Gradle Wrapper from 8.7 to 8.8

[junit-builds]

Combined PRs ➡️📦⬅️

✅ The following pull requests have been successfully combined on this PR:

• Closes #420 Bump Gradle Wrapper from 8.7 to 8.8 in /junit5-multiple-engines
• Closes #419 Bump Gradle Wrapper from 8.7 to 8.8 in /junit5-migration-gradle
• Closes #418 Bump Gradle Wrapper from 8.7 to 8.8 in /junit5-jupiter-starter-gradle
• Closes #417 Bump Gradle Wrapper from 8.7 to 8.8 in /junit5-jupiter-starter-gradle-kotlin
• Closes #416 Bump Gradle Wrapper from 8.7 to 8.8 in /junit5-jupiter-starter-gradle-groovy
• Closes #415 Bump Gradle Wrapper from 8.7 to 8.8 in /junit5-jupiter-extensions

This PR was created by the github/combine-prs action