Add Maven source plugin required by the release workflow

[michalvavrik]

Summary

Adds Mavan source plugin as Nexus has following rules:

2024-09-25T17:55:21.0380119Z [INFO] [ERROR] Rule failure while trying to close staging repository with ID "ioquarkus-1975".
2024-09-25T17:55:21.0390600Z [INFO] [ERROR] 
2024-09-25T17:55:21.0391898Z [INFO] [ERROR] Nexus Staging Rules Failure Report
2024-09-25T17:55:21.0393694Z [INFO] [ERROR] ==================================
2024-09-25T17:55:21.0395152Z [INFO] [ERROR] 
2024-09-25T17:55:21.0396550Z [INFO] [ERROR] Repository "ioquarkus-1975" failures
2024-09-25T17:55:21.0408622Z [INFO] [ERROR]   Rule "sources-staging" failures
2024-09-25T17:55:21.0413360Z [INFO] [ERROR]     * Missing: no sources jar found in folder '/io/quarkus/qe/flaky-run-reporter/0.1.3'
2024-09-25T17:55:21.0416798Z [INFO] [ERROR] 
2024-09-25T17:55:21.0418475Z [INFO] [ERROR] 
2024-09-25T17:55:21.0421406Z [INFO] [ERROR] Cleaning up local stage directory after a Rule failure during close of staging repositories: [ioquarkus-1975]
2024-09-25T17:55:21.0424257Z [INFO] [ERROR]  * Deleting context b0c9d983f655b.properties
2024-09-25T17:55:21.0426997Z [INFO] [ERROR] Cleaning up remote stage repositories after a Rule failure during close of staging repositories: [ioquarkus-1975]
2024-09-25T17:55:21.0430255Z [INFO] [ERROR]  * Dropping failed staging repository with ID "ioquarkus-1975" (Rule failure during close of staging repositories: [ioquarkus-1975]).

Please check the relevant options

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Dependency update
• Refactoring
• Breaking change (fix or feature that would cause existing functionality to change)
• This change requires a documentation update
• This change requires execution against OCP (use run tests phrase in comment)

Checklist:

• Example scenarios has been updated / added
• Methods and classes used in PR scenarios are meaningful
• Commits are well encapsulated and follow the best practices