SUID of sandbox helper binary is wrong on linux

[molikuner]

Describe the bug
When installing the desktop client on debian the file /opt/keeweb-desktop/chrome-sandbox has wrong permissions on the filesystem.
This issue isn't visible in the UI, as the application doesn't start and no error is shown.
When using the CLI to start KeeWeb via the KeeWeb command you get an error (view below).

I found that bug after upgrading from 1.8.2. Even a fresh install doesn't fix it.

To Reproduce

1. Download KeeWeb-1.9.2.linux.x64.deb
2. Go with your CLI to the download location
3. Install with sudo dpkg -i KeeWeb-1.9.2.linux.x64.deb
4. Start with KeeWeb
5. Observer the instant crash

Expected behavior
The application just works and starts after start without any further setup.

Environment
Debian Stretch: 4.9.0-9-amd64 #1 SMP Debian 4.9.168-1+deb9u5 (2019-08-11) x86_64 GNU/Linux

Logs

• The application doesn't even start, so logs from CLI:

29363:0826/210759.739348:FATAL:setuid_sandbox_host.cc(157)] The SUID sandbox helper binary was found, but is not configured correctly. Rather than run without sandboxing I'm aborting now. You need to make sure that /opt/keeweb-desktop/chrome-sandbox is owned by root and has mode 4755.
/usr/bin/KeeWeb: line 2: 29363 Trace/breakpoint trap   /opt/keeweb-desktop/KeeWeb

Workaround
The file permissions are after the install:
-rwxr-xr-x 1 root root 4.9M Aug 22 22:31 /opt/keeweb-desktop/chrome-sandbox
To fix it, you should use the following command:
sudo chmod 4755 /opt/keeweb-desktop/chrome-sandbox
The result is:
-rwsr-xr-x 1 root root 4.9M Aug 22 22:31 /opt/keeweb-desktop/chrome-sandbox
The application can start now.