[LTS] 1.3.0 maintenance update

[liplum]

Changes

• Fixed bug: Running runClient and runServer tasks failed on gradle 8.0+.
• Feature: Downloaded games file from GitHub will be put under $GRADLE_USER_HOME/mindustry-mgpp/games.
• Feature: Symbolic link of downloaded game files will be created under build/tmp/downloadClient and build/tmp/downloadServer.

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This discussion was created from the release [LTS] 1.3.0 maintenance update.