temporarily use 770 permission

[Tianhao-Gu]

spark_user@618d542b608c:/jupyterhub/users_home$ ls -ll
total 12
drwxr-xr-x 6 spark_user spark      4096 Sep 13 00:50 root
drwxrwx--- 9 spark_user spark      4096 Sep 13 04:33 spark_user
drwxrwx--- 6 tian.gu    jupyterhub 4096 Sep 14 03:34 tian.gu
spark_user@618d542b608c:/jupyterhub/users_home$ cd tian.gu/
bash: cd: tian.gu/: Permission denied
spark_user@618d542b608c:/jupyterhub/users_home$ groups spark_user
spark_user : spark jupyterhub

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 25.00000% with 12 lines in your changes missing coverage. Please review.

Project coverage is 68.08%. Comparing base (5dc6cdd) to head (65808b0). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/jupyterhub_config/custom_spawner.py	25.00%	12 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #89 +/- ## ========================================== - Coverage 72.48% 68.08% -4.41% ========================================== Files 5 5 Lines 229 235 +6 ========================================== - Hits 166 160 -6 - Misses 63 75 +12 ```

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