[BUG/FEATURE] Add support for OSTree based environments

[mariaWitch]

Describe the bug Doppler CLI does not install due to it installing files into a path classified as a system directory in OSTree based OSes. See: https://github.com/coreos/rpm-ostree/issues/233 This is caused by installing persistent files into the /usr/local/ directory, which is classified as a system directory, and therefore not writable on OSTree based OSes.

To Reproduce Steps to reproduce the behavior. Please include output from running the command with --debug.

1. Add the Doppler Repo to any OSTree based OS, such as Fedora CoreOS.
2. Attempt to install Doppler with rpm-ostree

Expected behavior Doppler should install properly without triggering the bug/unsupported behavior as described in https://github.com/coreos/rpm-ostree/issues/233

Screenshots

Desktop (please complete the following information):

• Guest OS: Fedora CoreOS
• Version: 36.20220820.3.0
• Host OS: Proxmox
• Version: 7.2-7

CLI Version: Version: ALL (As this is an issue with installing it, I would assume that this would effect most versions, but I am currently installing the most recent version for Fedora/RHEL/CentOS)

Additional context

[mariaWitch]

Doing some digging this can be easily resolved by changing the path for zsh for systems that use rpm so that they don't use the /usr/local/ directory in the package, I have created a pull request ( #332 ) that should resolve this issue. Note: I'm not entirely sure how this will affect users not on OSTree based OSes, but reading documentation suggests that it should not adversely affect anyone on a Fedora/RHEL/CentOS based OS.

[mariaWitch]

@Piccirello Looking for follow up on this and the related PR.