Crash during install of 1.7.27 on MacOS 12.6 `Failed to open juliaup config file.`

```
% curl -fsSL https://install.julialang.org | sh

info: downloading installer
Welcome to Julia!

This will download and install the official Julia Language distribution
and its version manager Juliaup.

Juliaup will be installed into the Juliaup home directory, located at:

/Users/ian/.julia/juliaup

The julia, juliaup and other commands will be added to
Juliaup's bin directory, located at:

/Users/ian/.julia/juliaup/bin

This path will then be added to your PATH environment variable by
modifying the profile files located at:

/Users/ian/.bashrc
/Users/ian/.bash_profile
/Users/ian/.zshrc

Julia will look for a new version of Juliaup itself every 1440 minutes when you start julia.

You can uninstall at any time with juliaup self uninstall and these
changes will be reverted.

✔ Do you want to install with these default configuration choices? · Proceed with installation

Now installing Juliaup
Well, this is embarrassing.

Juliainstaller had a problem and crashed. To help us diagnose the problem you can send us a crash report.
...
```

```
name = 'Juliainstaller'
operating_system = 'unix:OSX'
crate_version = '1.7.27'
explanation = '''
Panic occurred in file 'src/operations.rs' at line 675
'''
cause = '''
called `Result::unwrap()` on an `Err` value: Failed to open juliaup config file.

Caused by:
Permission denied (os error 13)'''
method = 'Panic'
backtrace = '''

0: 0x103a2df85 - core::result::unwrap_failed::ha988429942445917
1: 0x1038a9112 - juliaup::command_config_modifypath::run_command_config_modifypath::h1846bc244ac9ea63
2: 0x1037c296b - juliainstaller::main::h056e9fc82c1547cc
3: 0x1037ac166 - std::sys_common::backtrace::__rust_begin_short_backtrace::hcb7bab99fdf20ecc
4: 0x1037ac4f2 - std::rt::lang_start::{{closure}}::h1e9d1356e183e5d3
5: 0x1037c6f82 - _main'''
```

`rm -rf ~/.julia/juliaup` didn't fix it

Reproduce the install with `curl -fsSL https://install.julialang.org | sh` on the reported macOS setup, then inspect `src/operations.rs` around line 675 and the `command_config_modifypath` path shown in the backtrace. Determine why opening the Juliaup config returns permission denied and verify the installer no longer crashes when that operation fails.

Written by the indexing model from the issue text.