Fix dubious ownership problem

[Kuniwak]

unity-meta-check via GitHub Actions unexpectedly exit with status 128.

...
info: skip package "com.unity.modules.vehicles" because it does not exist: Packages/com.unity.modules.vehicles
error: exit status 128
##[debug]Docker Action run completed with exit code 1
##[debug]Finishing: Run DeNA/unity-meta-check@v3

then, set log_level to "DEBUG":

...
debug: searching: "/github/workspace"
debug: exec: git -c core.quotepath=false ls-files (on "/github/workspace")
debug: stderr: fatal: detected dubious ownership in repository at '/github/workspace'
debug: stderr: To add an exception for this directory, call:
debug: stderr: 
debug: stderr:  git config --global --add safe.directory /github/workspace
error: exit status 128

Related: actions/checkout#760

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[Kuniwak]

I confirmed that the problem was fixed at v3.1.4-alpha0. I'm investigating why test was failed.