tools: hv: lsvmbus: change shebang to use python3

In many modern Linux distros, running `lsvmbus` returns the error:
```
/usr/bin/env: 'python': No such file or directory
```
because 'python' doesn't point anywhere.

Now that python2 has reached EOL as of January 1, 2020 and is no longer
maintained[1], these distros have python3 instead.

Also, the script isn't executable by default because the permissions are
set to mode 644.

Fix this by updating the shebang in the `lsvmbus` to use python3 instead
of python. Also fix the permissions to be 755 so that is executable by
default, which matches other similar scripts in `tools/hv`.

The script is also tested and verified that is compatible with
python3.

[1] https://www.python.org/doc/sunset-python-2/Signed-off-by: Anthony Nandaa <profnandaa@gmail.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20240702102250.13935-1-profnandaa@gmail.comSigned-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20240702102250.13935-1-profnandaa@gmail.com>

tools/hv/lsvmbus

-#!/usr/bin/env python
+#!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0
 
 import os