hornet: Unable to deploy the private tangle on Ubuntu

Describe the bug

Got snapshots creation error and permission denied when trying to deploy private tangle on Ubuntu 20.04.

To Reproduce Steps to reproduce the behavior:

• clone hornet and checkout v2.0.0-alpha6
• goto private_tangle folder
• run ./bootstrap.sh

Expected behavior

The ./bootstrap.sh should spin up a private tangle on local PC without problems.

Environment information:

• OS: Ubuntu 20.04
• docker version 19.03.13
• Docker Compose version v2.3.4
• HORNET version v2.0.0-alpha6

Additional context

[+] Running 0/1
 ⠿ create-snapshots Error
[+] Building 261.4s (21/21) FINISHED
...
error: unable to create snapshot file: open /app/snapshots/coo/full_snapshot.bin_tmp: permission denied
...
2022-03-31T15:00:40Z    PANIC   Database        could not create database dir 'privatedb/tangle': mkdir privatedb/tangle: permission denied
github.com/gohornet/hornet/pkg/node.(*Pluggable).LogPanic